Obviously, I understand that MMA is a respectable sport, which consist of talent, skill and huge discipline (to be successful at it) and I know what you're saying, but if we're talking about proper role models, in theory, smoke MJ or not, be a crackhead or not, do porn or not, what kind of a role model to children is a guy who beats up others for a living?
You mean like Bruce Lee, Superman, the soldiers that defeated Hitler etc.?
Fighting isn't inherently bad, not in certain contexts and especially not in a sport.
Taking it up the pooper for money though ...