You agree that it is wrong, so "wrongdoing" seems not to be the issue. As for "sexual": Why is it creepy? Because it normalizes sexual violence.
No, that's not my reason for finding it creepy. Were these make-believe women involved or simply pictures found on, I dunno, tumblr or whatever I'd have literally no issues with it. I find it creepy when the women involved were people they know. I don't believe - as a quick glance at the games on here I'm currently involved in - that rape fantasies in general normalise sexual violence (and, in other news, I don't think I'd classify actions that did as "creepy" - just not the word I would use).
As an aside to the college rape discussion - I just read this
and found it quite interesting.
ETA: Ha, forgot to make my actual point. So no, that's not why I find it creepy but also it's a distraction from, as I see it, the issue. Whether that was why I find it creepy or not, the fact remains that using the "toolbox" we have for addressing campus rape is not appropriate for addressing every single situation, trivially, and IMHO not appropriate for addressing this situation.