This is not merely a nice, and likely true, explanation is an interesting textual feature. Rather, there are some interesting possible ramifications of adopting such a position.
For example, many interpret the Rambam's 8th ikkar of emunah to be that not a letter or word of Torah has changed from the time it was given, in the strictest sense. (Read up that principle here; it might just mean that Moshe did not innovate anything of his own, rather than it being Torah min hashamayim) Yet if what I suggested is true, the strict interpretation does not hold true, for here is a word they were willing to consider was not original.
Another possible ramification is to the age of trup. As Shadal proved, many medieval meforshim understood the trup to be the work of some intelligent human author, conveying his own opinions, rather than being miSinai. And therefore, they felt free to argue with it. Meanwhile, other rabbinic figures saw fit to ascribe Sinaitic origin to the trup.
If trup were miSinai, then there should be no question here. Look at the pasuk: there is a darga on Moshe and a tevir on veAharon. The former accent is the mesharet of the latter. And the darga would not appear without a tevir. If the trup had been set from Sinai, then there should have been no question about the word. Unless somehow two parallel versions of the trup had developed, something more difficult than a scribe merely mistakenly adding or deleting a word...