While I was in the Marine Corps, I knew of two incidents of male-on-male rape.
Once while in Okinawa - just as you described - drunk Marine awakes to his roommate smoking his pole. He started beating the shit outta him and it two or three other Marines to save the smoker’s life!
The other was in Camp Lejeune. We had three-man rooms at our barracks and the three roomies went drinking, one passed out and the other two decided to hold him down and sodomize him. His screaming brought the three roomies from the adjoining head into the room, at which point all four of them kicked the ever-loving-shit outta the two offenders.
In both cases, a quick ass-kicking response left the offenders bloodied and bruised which included a side trip to the hospital on the way to the brig! In neither case were the responses admonished (as it should be)!
I think most of these attacks are not even reported. The victims really don’t want to deal with the embarrassment of having the event exposed.