See, the thing about statutory rape is that it is illegal, and sexual assault is also illegal, but (surprisingly!) that does not mean that they are the same thing. (It is left as an exercise for the reader to see if this applies to other pairings like, say, "public drunkenness" and "murder in the first degree.")
Stallman was not "defending statutory rape": he was saying, "Words mean things, and the words "sexual assault" suggest an image of 75-yr-old Marvin holding girls down and raping them, and that it is unlikely that that, you know, actually happened."
>It was a very creepy situation and indefensible.
Oooh, so creepy! Too creepy to think about, even! Nazis were pretty creepy: let's accuse them of violating the CFAA, before there were computers! Anyone defending them against this is defending Nazis, and worse, creepy Nazis! They are likely creepy as well! This creepy stuff seems to be contagious...
Since it can't be made too visible, Stallman's actual comments: https://www.documentcloud.org/documents/6405929-091320191420...
There was some irrelevant quibbling about how accusations are worded.
Then there was the speculation that the seventeen year old girl who is accusing his 73 year old friend of a sex crime would have appeared willing in the exchange with the implication that this apparent willingness made the situation not Minsky's fault.
Doesn't matter if it didn't happen, defending statutory rape like that is really inappropriate, and with a ~60 year ago gap it doesn't really matter about the details. It was a very creepy situation and indefensible.
Stallman was defending it, it wasn't just some intellectual problem with the wording of accusations.
Not a witch hunt, not a victimization of an innocent intellectually curious man, it was a measured and reasonable response to a very inappropriate conversation.