Honestly, my guess is that this is a matter of threateningness, and that the disparity is due to the fact that most people are cis and straight. Given that almost all cismen are physically stronger than almost all ciswomen, and you didn’t indicate that the victim was in any way restrained, I bet people of different genders would tend to have different assumptions about how much control they have over the situation.
Straight cismen would often think “OK, that’s cool, and if she does anything I’m not OK with, I can just physically shove her off of me”, while straight ciswomen think “OH MY G-D I’M TRAPPED THERE’S A HUGE PERSON ON TOP OF ME HELP”. Given that we already know the person in question is a rapist, “You will have to use physical force if you want to escape” is pretty much a given. The fact that one group of people is so shot up on naturally-produced steroids that they don’t have to worry about losing such a contest seems like enough reason for this scenario to not freak them out.
Thus, straight cismen are likely to say “negative” just when your scenario seems like an unpleasant violation, while straight ciswomen are likely to say “negative” for that reason or if they have ANY SENSE OF SELF-PRESERVATION.
(For reference, my first thought when I saw this was “Having a stranger do that sounds violating and I wouldn’t want it, but at least I can just throw that person off of me and leave the room”. If I were straight or was taking anti-androgens, I expect my response would have been quite different.)