Well Alter, funny thing is I used to have more violent urges in my youth, and that was also the time I used to fight "professionally" much more often. I don't know if it's a connection, maybe the kickboxing helped, true. But maybe it helped encourage my violent side and the expression of violent emotions, maybe it gave me enough confidence to "take the shortcut" and use my body instead of my reason to get my point across. I think I'm more mature now, and the close calls I've been through are helpful reminders when I feel my control is about to fly off the window.
In TNP's case, even if there is a sexual component, I still think he should stay away from playing with this shit if he can end up killing someone. If I had his problems, I know I would, even if my sex life had to suffer. And that means a lot, I'm quite a sexual creature. I don't think putting himself in any form of power over someone else's life is a smart thing, be it in the bedroom or in a fightclub. I'm sure he's smart enough to control himself if he's away from the temptation, it's not like he's the type to attack someone's throat on the street or something.