He has a long history of using forums meant for technology discussion to promote borderline (and that's generous) social opinions, and of being openly hostile to people who don't tow his line. In this instance he ridiculously downplayed the most egregious instances of sex trafficking of minors, by a horridly evil individual... who happened to donate almost a million dollars to him!
His previous comments about minors on his personal blog, which I don't even want to dignify with a description (you can do your own search), leads me to wonder what other connections than money he had with Epstein.
For all of us that don't worship Stallman - I consider him a net negative to the FOSS movement - this has been a long time coming. It would have been a deserved resignation in a normal social environment.