You're looking for a bias that just isn't there. Our society most definitely has a problem with rape and sexual assault— specifically towards women— but I don't see any Twitter users making the assumption that "t-shirt advocating rape" == "t-shirt advocating rape against women" There are men who are victims of sexual assault and rape, and you do them a disservice by ignoring them to push your own agenda.
Several of them include the #NotBuyingIt hashtag, a hashtag specifically related to sexism against women.
I really hesitated to respond to you again, at this point it seems you are doing nothing more than post hoc rationalization of your original inaccurate assertion.
I should also clarify that I am in no way arguing that rape is equally a male and female problem. Women deal with rape culture much more than men. My argument is that I don't believe these twitter users were upset because it was targeting women. I think they were upset because rape is a terrible thing to happen to anyone.