Stallman literally said a sex-trafficked child wasn't a "rape victim", and this isn't the first time he's espoused, on technical mailing lists, that golly, 'age is just a number' when it comes to children having sex with adults. He's an infamous serial sexual harasser - for decades. Threatening to kill himself if women won't date him, hosting barely-clothed "cuddle puddles" on the bare mattress in his office at MIT, and women in his office building stuffing their offices full of house plants because Stallman was known to hate them, and it was the only thing that would make him leave women alone.
When Redhat and others pulled funding, the board was clear they weren't interested in prudent governance of the organization, but solely about petulantly supporting their geek deity. His refusal to step down, and the board's refusal to remove him, irreparably harmed their reputation and finances.