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.