That's a misrepresentation what Stallman said. The source you quoted frames it as though he's claiming the victims were "entirely willing" to be trafficked when he actually said

We can imagine many scenarios, but the most plausible scenario is that she presented herself to him as entirely willing. Assuming she was being coerced by Epstein, he would have had every reason to tell her to conceal that from most of his associates.

Criticize what he actually said, not a fabricated portrayal of it.