That was not Stallman's statement.
In fact, Stallman's argument rests on the foundational belief that the girl was forced to service Minsky.
He reasons that because it would have been in the best interest of Epstein not to disclose the harm that's being done to the girl, she would have been convinced to present herself to Minsky as willing. Thus it is argued that Minsky might have had a sexual encounter without having realized that the girl is being forced to do this. In such a scenario, it is proper to accuse Epstein of harm, but wrongful to accuse Minsky of sexual assault.
All participants of the discussion should refer to the original MIT email thread and not base their opinions on secondary information. There is also a quote from a scientist who names himself as an eyewitness and clears Minsky of wrongdoing. He was not listed by the girl as present during the event and it may be too early to accept his words as the truth. However, if the girl's account corroborates his, then even the harshest critic should be obliged to exonerate Stallman's statement.
It reminds me of the role of the lead in "Twelve Angry Men".