I think the biggest conflict here is the fact that most people are not actual pedophiles or sexual assault defenders; however, many may have confused, internally inconsistent or overly simplistic views on those topics. To that end, I really think you need to put on a Stallman hat to understand his viewpoint. (Not that I’m not saying this is something you should wear normally, this is just an attempt to interpret his words in good faith.)
Seeing through those lenses, I think the point being made was that Stallman believes the situation was that Minsky was unwittingly approached by a girl who had been coerced by Epstein to present herself as being of the age of consent and genuinely interested in him, and he felt that the term "sexual assault" in this case was unfair as it projected the view that Minsky had done something coercive, similarly to how someone who buys something that was stolen is unknowingly "trafficking in stolen goods". His views on statutory rape are, IMO, fairly straightforwards: he clearly subscribes to the "if the law says it is legal tomorrow but not today there is something unsatisfying about its definition" viewpoint.
Now, these viewpoints have multiple issues, the largest of which is probably that one is supposed to do due diligence in their choice of partners to ensure that they are what they seem and not underage or being coerced, especially if one is a 73-year-old man with a woman half a century younger. And the reason we have a specific age set in law is that otherwise we would have to do exceptionally difficult value judgements on whether a person is mature enough to provide consent. But I think both of these are just the failings of a rational person to make sense of the world, rather than the rants of a deranged and actively malicious lunatic as most people (including you) claim.