A strange use of the word "disembark", can it have a meaning "to move"?

Here is a sentence from a newspaper article:

The new foray [President Trump's statements about the voter fraud] into such a sensitive topic is not likely to go over well with Republicans in Congress, who are boarding buses and trains to disembark Washington for Philadelphia and their annual policy retreat — this time with a Republican president and vice president who are expected to attend.

I understand the general meaning of the sentence, that now, the recent words of President Trump have pretty good chances to materialize into some legal action. But I cannot understand the part about Republicans boarding buses, highlighted with bold.

The word disembark in my dictionary and in the reference provided by Google has only one meaning: to leave a ship, aircraft, or train (or other vehicle). So its use here confused me, because it looks like the Republicans are boarding buses in order to disembark in Washington and then move to Philadelphia for their annual policy retreat. But this is something like a nonsense (why can't they board trains directly to Philadelphia?).

The common sense is suggesting that they are moving from Washington to Philadelphia, but this does not coincide well with the dictionary meaning of the word "disembark".

So could anyone clarify this for me, please?

Here, the word disembark is being used to mean to leave, ie the Republicans in Congress are boarding buses and trains to leave Washington for Philadelphia to go to their annual policy retreat. Technically speaking disembark should only be used for leaving vehicles such as ships or aircraft, perhaps here the journalist is viewing Washington itself as a vehicle for policymakers? Or perhaps they are simply unfamiliar with the word and used it incorrectly.

At the very least the writer has used the word poorly, since a probable metaphorical meaning ("Do X, to get out of the city") is right next to an obvious literal interpretation ("board buses and trains, to disembark [from those buses and trains]...").

Really, though, the entire reference to transportation is unnecessary; the sentence would have just as much information if the phrase were "who are headed to Philadelphia for their annual policy retreat."

The article you quoted and linked to has been heavily revised, and the paragraph in question removed. It wouldn't surprise me if the clearly odd usage of disembark was a factor in that edit.

The root of disembark derives from the Latin barca, meaning 'boat', and historically the term applies specifically to exiting vehicles. Interestingly, however, the word embark can mean both boarding a vehicle and beginning a course of action. One can embark on a journey, a new career, or a risky endeavor. More to the point, the phrasing "they are embarking for Philadelphia" seems perfectly normal. It may be that the author simply stumbled when trying to include the point of departure, resulting in the awkward usage of disembark.