ditching Twitter as far as I see has no downside.
I'm curious: have you ever liked Twitter?
Because i could understand not seeing any downside to leaving a site if one has never actually liked it. But, many people liked (and still like) Twitter. I personally have known many interesting people there, and even started some nice in-person friendships. I don't like at all what's become of Twitter; i have it now blocked through the LeechBlock extension so i don't fall into doom/shit scrolling. But i think there's still some good in there. I can totally understand how many people would find it difficult to fully leave; myself included.
It's a one-time error the maintainer made 3 years ago (at a time when much of the US-influenced west was going crazy with polarization over the use of pronouns), not a consistent behavior of intolerance as one would expect given the level of hostility towards the project seen here. I personally find it weirder to hold such a long-standing grudge for a one-off error, and over a project one is not even personally involved with.