But asking what the author would gain from fabricating it is a terrible reason to believe something. Pathological liars exist and they prey on people with such low bars for belief.
I think it's exceedingly rare for an outstanding technical contributor like Matthew Butterick to also be a pathological liar, especially in ways that would hurt their own career.
Both of these are great questions, I wish situations like these were resolved with a recorded conversation between at least the accuser and someone who attempts to be unbiased that was involved.
I recently had an acquaintance get cancelled who held pretty troubling religious opinions, but outwardly the way he treated everyone was better than the vast majority of people treated others in that community. I feel like a conversation would've resolved that issue without him losing 3 positions, one of which being his job.
I don't know enough about this particular situation to have an educated opinion.
But in my experience with these kinds of situations, people often misconstrue and sometimes even knowingly misrepresent them not because a rational reason to fabricate them, but just because of one or the other irrational psychological reason to do so. People are not rational, and the mere fact that they wouldn't get anything doesn't mean that they would do it.
Maybe you misunderstood my post, I don't disbelieve him. I'm raising concerns that there's apparently brazen abuse happening amongst many accomplished adults with nobody being held accountable for it.