Word meaning "expressing innocous concept with offensive near-homonym"
Years ago, an Internet NNTP poster's signature read in part "a niggardly lover".
Of course, "niggardly" just means "stingy", so there was nothing literally offensive in his signature.
However, I believe he chose this phrasing (instead of "stingy lover" or "miserly lover") specifically to provoke and annoy people.
What word embodies this concept? Using an intentionally offensive-sounding phrase to express an otherwise inoffensive concept?
Would this be the opposite of bowdlerization?
It is an interesting approach to baiting people. Bowdlerization and other forms of censorship could be considered "opposites" to this. I tend to prefer the contrast with the idea of minced oaths:
A minced oath (also pseudo-profanity) is an expression based on a profanity or a taboo term that has been altered to reduce the objectionable characteristics. ... The most common methods of forming a minced oath are rhyme and alliteration.
Meanwhile it shares many similarities with eggcorn:
An eggcorn is an idiosyncratic substitution of a word or phrase for a word or words that sound similar or identical in the speaker's dialect. The new phrase introduces a meaning that is different from the original, but plausible in the same context, such as "old-timers' disease" for "Alzheimer's disease". ... Eggcorns often involve replacing an unfamiliar, archaic, or obscure word with a more common or modern word
The user seems to be attempting to create a malicious eggcorn in the reader's mind, replacing an archaic term with a more modern (and offensive) one. Indeed, seeing as the original word was primarily negative, a racial slur could introduce a meaning "different from the original, but plausible in the same context."
There have been numerous public controversies over this particular word pair. (Controversies about the word "niggardly")
Ultimately, though, I think the word to describe this behavior best might just be "trolling."
If it is indeed deliberate, OP's example is a form of asteism (genteel irony; a polite and ingenious manner of deriding another). Depending on one's preconceptions, it may be considered subversive, provocative, or couched language.
It's not dys-/mal-/cacophemism, because all of those imply that the actual words used are inherently offensive. I'm well aware that there have even been lawsuits in America arising from the word niggardly - but even where the complainants won their case (most didn't), no lawyers ever argued that the actual word was offensive.
It's almost the direct opposite of a minced oath, since the intention there is to avoid giving offense. So much so that one hears berk (slang: fool) used in polite society by people who may actually be giving offense without knowing what they are doing.