That's a fact of human nature. You will see the occasional case where a drunken man has his sexual integrity violated (on a narrow definition of rape, you can't rape a man because he doesn't have a vagina). For instance, there was a case a few years ago where a military officer was convicted of sexual assault after he inserted a cigar tube into the orifice of a passed-out male fellow officer. However, the simple fact is that there are just many less people with the desire to insert a body part into a man's orifices than there are who have the desire to insert a body part into a woman's orifice(s).