Not Lemmy specific. There was US legislation related to the word being deemed offensive fifteen years ago (given the slow nature of Congress, it wasn’t a new sentiment then, either): https://en.m.wikipedia.org/wiki/Rosa’s_Law

Fair enough that plenty of insulting words could be cast as abelist: but my guess is that a word like “idiot” is old enough that most folks called that in a medical context aren’t around any more. Maybe I’m wrong though: plenty of folks do push against saying things like “crazy” in an insulting manner.