I just can't believe that. I mean I know some people are sick enough to do things like that, and Ulli did post an article once on the forum that showed that Arabs had tied up Orangutans in this one place to use them sexually. However without completely tying the apes up and immobilizing them, I think it would be very hard for a man to penetrate a chimp against its will.
We all know how powerful Travis was, right? They're all strong enough to take a fully grown man and toss them over the fence like they were a banana. Not to mention that when they go into attack mode, they attack people's faces and genitals, especially men on the last one. If they did this to a rival chimp, they would make sure that other chimp wouldn't be producing any offspring, that's why they do it. I don't see why any human would present his genitalia to an unbound chimpanzee unless he wanted a sex change operation.