I didn’t interpret Stallman’s comment to mean this at all. But rather that Minsky assumed that the victim was engaging in prostitution and willfully engaging in sexual acts in exchange for money.
With regards to not knowing someone’s age, there are a few plausible scenarios that come to mind. The victim could have lied to Minsky. Epstein could have lied to Minsky. She could have presented a fake ID, etc.
I think you making a lot of assumptions here that just aren’t borne out by the evidence available. Assumptions about what Stallman thinks or has implied, and assumptions about the nature of the accusations against Minsky. As far as I am aware we don’t know where or when it allegedly happened, the victim’s age at the time, or the details of how it was initiated. Some of the details you are assuming about the victim being 17 or the encounter having occurred on a private island seem to have been pieced together in a highly speculative verge article or from internet commentators (if you have quality sources of information that report otherwise please share). Stallman may not have had these details in mind or may have had a different set of assumptions when he wrote what he did.
I for one would like to see Stallman elaborate on some of his positions to better answer these questions. Not silenced.