Then why didn't these women report him to the whoever competent authorities at MIT? Or to the police if the crime is serious enough? Why are they signing an open letter on the internet instead?
Please don't parrot unfounded heresy.
And I'm not talking about the horrific behaviour towards opposite sex, or other unprivileged groups. Tales of "I idolized RMS and thought he was at worst a bit hippy in behaviour then I met him and now I never want to again" tended to move word of mouth, sometimes with background feeling of "do not want to rock the boat, I want Free Software to flourish".
For the same reason that Epstein, Weinstein, or Cosby had a huge number of victims that didn't report anything: each victim individually calculated that reporting it was far more likely to wreck their career than achieve anything positive.
He is abusive against everyone around him. He has sexually harassed numerous women near him, to the point that people lock themselves in their offices when he visits.
He is incredibly, incredibly toxic. He has had a huge crowd of people trying, again and again, to tell him to stop acting like this, and to be a decent human being. He refuses.
He is a massive burden on any institution he is part of. Kicking him out is the correct decision in every case, no matter what he has achieved in the past.