Valid point.
In the words of sex columnist Dan Savage (who is gay, btw) , what people seek is not deviation, but variation.
I won't be the first to admit that some CD'ers find thrill in the roleplay with having sex with a man, they exist.
Not my thing. .....that's just me.
I don't know if this applies to your male friend, but I get the sense that some people are just complicated.
My explanation of me is simple: I just want freedom to express myself, and i don't like the rules society imposes on people without justifcation. I'm about as boringly monogamously hetero as it gets.