What did President Trump mean by "crusty voice"?
Trump recently referred to John McCain as a "crusty voice in Washington."
"I can tell you, we hope John McCain gets better very soon because we miss him. He's a crusty voice in Washington, plus we need his vote, ..."
I've never heard that term. Does it mean something? Or did Trump make it up on the spot?
To be clear, I'm well acquainted with the term "crusty," but have never heard it used in conjunction with "voice." "Crusty" is generally an insult, but Trump seems to mean it as a compliment, leading me to wonder whether "crusty voice" is some sort of obscure idiom. Judging from responses, it sounds likely that this is just another example of Trump's fast and loose approach to English.
EDIT: As for my research, the only instances of "crusty voice" I can find on the internet are references to this very speech.
Instances of 'a crusty voice' in the wild, 1831–1959
The expression "a crusty voice" has appeared a number of times over the past 200 years in the context of a (usually unseen) source of speech. The earliest instance that a Google Books search finds is from "Patronage" in The Philadelphia Album and Ladies' Literary Port Folio (September 10, 1831):
There the judges took their seat, Patronage on the right, and Criticism, with a scourge in her hand, upon the left. "What yields the press to-day?" cried a lean scribe, who sat before desk in character as clerk. A crusty voice from the assembly answered—hiccup—nothing. And the Court rose to adjourn, when a tall, lank gentleman, from the ranks of Ignorance, by the assistance of the arm of Impudence, advanced to the front of the forum, and thus commenced:— ...
From "Henrietta and Vulcan," in The Continental Monthly (April 1863):
'Mr. Landon Snowe, Miss Fanny,' said a crusty voice, and from under a tower of white turban, Sibyl's face looked out—at the door.
'We will see him here, Sibyl,' said Fanny, brightly; 'and oh, Sibyl, ask Mott to make a macaroon custard for dinner, for Miss Ruyter.'
From Ferdinand Sarmiento, Life of Pauline Cushman: The Celebrated Union Spy and Scout (1865):
"What's the matter? Can't you let a man sleep when he's paid for his bed and all?"interposed a crusty voice from the room in which the old bachelor lay.
"Oh, gentlemen! oh, gentlemen! is there any thing the matter?" cries here the old maid next door, making her appearance, with a modest simper, in a costume improvised for the occasion, and which resembled the retreat of an ostrich, inasmuch as it concealed perfectly her head while it exposed two long spindle-shanks that were scarcely objects of beauty.
From Muriel Hine, "The Tragedy of a Tiff," in Cassell's Magazine (July 1901):
"We're due at York at 11.20, I believe, madam," came a crusty voice from the third occupant of the carriage, a shrivelled old man muffled in a heavy overcoat despite the warm June afternoon.
"At York possibly," Eve politely acquiesced ; "but we get out at Northwick."
From Daniel Christenberry, The Semi-centennial History of the Southern University, 1856-1906 (1908):
The Doctor [Wadsworth] was not so fortunate at another time. The hour for declamation had arrived, and, at least one faint-hearted victim was not ready. Seeing the Doctor busy in his room, the truant speaker stealthily locked him in and left the key outside. There was no declamation that afternoon, but a crusty voice from a second-story window wooed the smiling and polite lad to the Doctor's prompt release.
From James Ford, "The Ethel Barrymore Following," in Appleton's Magazine (November 1908):
"Oh, well, what she's doing now isn't of much consequence. I've no doubt she'll be glad enough to let the others act and sit down for a little talk with me. Besides, I'm awfully afraid she'll give us the slip and go to supper somewhere else. She's very much in demand now, you know."
"Well, I call that a fraud," said a crusty voice on my right. "If Ethel doesn't come to supper I'll be sorry I came. Why, you know we were positively promised that she'd be there; and she's so ornamental at table."
From Kenyon Gambier, "The Huge Black One-Eyed Man," in the Saturday Evening Post (June 23, 1917):
He stopped at length in front of a garage, shattered the peace with the toot of his horn, then got out and pulled an iron rod, which proved his suspicion correct, for a bell jangled within, a crusty voice from a window above called "Coming," and an elderly man at length opened to him.
From an unidentified article in National Geographic Magazine (July 1925) [combined snippets]:
It seemed, too, as if I had not slept more than a few minutes before rude hands were shaking me and a crusty voice was calling me from a far world.
"Mr. Hall! Mr. Hall! Quarter of four! Mr. Page says it's pretty wet on the bridge. Are you awake, sir? Weather's tough. Everybody's sick. Do you hear me? Mr. Hall! Mr. Hall!"
From "Jep Coney's Thresher," in the [Sydney, New South Wales] World's News (December 21, 1932):
He [Jep Coney] was up before daylight, and while he raked out the red embers that had been banked overnight a crusty voice shrilled from the bedroom: "Jep, where's me leg? Drat it, everything's goin' amiss on this farm."
"What did you do with it last night?" asked Jep, still raking.
"I stood it against the wall," she [Pegleg Biddy] said.
From "Three Cars of Cops Race to Nude Girl," in the Santa Cruz [California] Evening News (September 26, 1935):
San Diego, sept. 26.—(AP)—"You had better send some more cops to the municipal golf course for the sake of morals and young children. There is a nude girl up here," a crusty voice said to Police Captain Robert Newson over the phone.
A few moments later three radio cars were at the scene.
From Margaret Henrichsen, Seven Steeples (1953) [combined snippets]:
One afternoon my telephone rang and a crusty voice said, "Mrs. Henrichsen, can you come up here at seven o'clock tonight?" I recognized the voice as belonging to one of the older men of the town— a man who had for years owned a quarry and was used to having his own way. His tone was more command than question.
And from an unidentified article in the Saturday Evening Post (1959):
"We're going to give this thing a try before the general shows up."
That was a pious hope that didn't work out, because just then a car rolled to a stop in the parking space and a crusty voice growled a familiar salutation. "What the hell goes on here, hey?" General Tingle belonged to the Old Army "hurry-up-and-wait" school, and so he'd come almost a half hour early. Duncan mentioned a few choice McNab oaths under his breath as he saw the Old Man's shadowy figure coming toward him— ...
Of the eleven examples listed above, four explicitly identify the source of the "crusty voice" as being an "old bachelor," "a shrivelled old man," "an elderly man," and "one of the older men of the town"; a fifth refers to the source of the voice as "the Old Man," but that's common army slang for a general. Still generals do tend to be fairly advanced in years, and two of the other six characters are likely oldish, too: the professor locked in his office and unable to proceed with his declamation examinations, and "Pegleg Biddy"—a name that by no means suggests a spring chicken.
So one characteristic that seems strong in these examples, insofar as it can be traced at all, is that "a crusty voice" is often associated with someone who is old; that is, it suggests a dried, cracking, perhaps scratchy voice.
Reference-work treatment of 'crusty'
According to Merriam-Webster's An American Dictionary of the English Language (1847), crusty has long also had connotations of crankiness or irascibility:
CRUSTY a. [1.] Like crust; of the nature of crust; pertaining to a hard covering; hard; as, a crusty coat; a crusty surface or substance. 2. Peevish; snappish; morose; surly; a word used in familiar discourse, but not deemed elegant. {In the old writers, CRUST is used.}
By the time of Webster's New International Dictionary (1909), the second definition of crusty had changed somewhat:
crusty a. ... 2. Having a harsh exterior, or a short, rough manner.
And in Webster's Seventh Collegiate Dictionary (1963) it has morphed into this form:
crusty adj ... 2 : SURLY [defined elsewhere in the dictionary as meaning, variously, "arrogant, imperious," "harsh, rude," and "menacing, threatening"], IRASCIBLE ["marked by hot temper and easily provoked to anger"]
but with this further note distinguishing crusty from such similar terms as bluff, blunt, brusque, curt, and gruff, all of which "mean abrupt and unceremonious in speech and manner":
CRUSTY suggests a harsh or surly manner sometimes concealing an inner kindness;
Merriam-Webster's Eleventh Collegiate Dictionary (2003) alters the tenor of its predecessor's definition only slightly:
crusty adj ... 2 : giving an effect of surly incivility in address or disposition
Barbara Ann Kipfer & Robert Chapman, Dictionary of American Slang, fourth edition (2007) brings us almost up to date on crusty:
crusty adj Gruff; surly; ill-tempered; FEISTY : Crusty George Meany. The downturned lips, the jowls, the half-closed lids, all were dour (1834+)
The quotation about George Meany, by the way, is from an obituary for Meany titled "Labor's Voice Is Stilled" in Time magazine (1980). Meany died at the age of 86, and the crusty image of Meany in the obituary seems to emphasize his physical characteristics as an older man as well as his irascibility. Still, none of the reference works that I consulted shows any explicit awareness that "crusty" shows up a disproportionate number of times in descriptions of older people.
Conclusions
If we can assume that Donald Trump has a clear understanding of the meaning of crusty as applied to people and their voices (we can't), we might conclude that the statement that the poster asks about amounts to saying "He is a surly voice lacking in civility, plus we need his vote."
In my view, however, the dictionary treatments of crusty are accurate only to a rather modest point. One might translate the statement far more positively as follows: "He is a blunt voice—plainspoken to the point of roughness, but possessed of an inner kindness; cantankerous, but not vindictive; the voice of an old man who does not suffer fools gladly, but suffers them as he must." Of course, I can't honestly assert that Trump meant to say those things either.