Mens rea ("guilty mind" aka criminal intent) is an important element for many crimes. People - generally - are inconsistent with regard to how much they think impact matters for a crime and how much they think intent matters. The law is also inconsistent, with itself, and with the opinions of the citizenry. In this case, US law (but not the laws of all countries) makes sex trafficking and statutory rape strict liability laws - only impact matters, not intent.
Stallman raised the question of Minsky's mens rea, suggesting that Minsky might not have had any criminal intent at all. To people who feel that mens rea should always be a criteria in criminal and moral judgement (such as myself), the existence or lack of existence of mens rea matters to Minsky's moral culpability.
With all that in mind, I'm dubious that Minsky could have been approached by a young woman and not had some degree of mens rea. At the very least, Minsky must have assumed the woman was a paid sex worker and recognized at least some possibility that she was trafficked and/or underage. I can't abide the notion that a old man would have mistaken the invitations of an uneducated young girl as genuine attraction.