What kind of person just has ice cream that they don't enjoy?
All I mean is that lust and conscious morality don't always see eye to eye. People might consciously recognize that rape-fantasies are awful, but they can't help but be turned on by them. I mean, you figure for thousands of years the very idea of lustful sexuality was considered amoral, but we all know people were still grinding genitals in back-alleys and hay-stacks across the world. Didn't mean they were all libertines - plenty would have agreed that extra-marital screwing was bad, but they did it anyway.
So fast forward to now, where we all agree rape is a traumatic thing that shouldn't be treated lightly. Doesn't mean there isn't people fantasizing about. And those people fantasizing will mostly agree rape is a horrible thing. They just diddle themselves, feel dirty, and move on.