Stallman decided it was a great idea to, in the wrong place at the wrong time and in response to a protest regarding someone he knew (Minsky, not Epstein), construct a hypothetical that exonerated Minsky and then judge that protest, again publicly, through that hypothetical. That's not a "believe he said" thing. That's what he did. He got tossed out on his ear for that and that's a thing he did.
Now, RMS then did construct a hypothetical based on his knowledge of Minsky's character. Note that nowhere in his hypothetical did he either defend Epstein or assert that the victim was in fact willing - both of which were things that he was accused of doing. He then insisted that people be more precise in their speech, which is exactly what you should do if you want actual justice.