Okay so it's not that he was doing a bad job or that they found someone else who would do a better job, and it's not that he broke any explicit FSF rules or refused to obey an FSF rule.

It's thought-crime, essentially. He had strong and unpopular ideas, sany people disliked him, so he's bad for the FSF's image.

But you could argue that that kind of creativity, the inclination to ignore convention and forcefully invent and argue for your own vision of that world - that's a requirement for the job of leading the FSF.

I haven't had time to start doing my own research about him (given how influential he was in the course of 20th century history) but I will.