If they want to sure...

It's there life they're risking! It's not gonna effect me if they break their back

I don't see what the problem is. People end up hurt during a fight, why not just before. It's not like they're going to get much more hurt than they already are. I mean, how much more mentally challenged can you get if you climb into the ring? Plus if they allow little people to participate, it will be that much more entertaining ;)

I want to see how difficult it is to hit a person with Parkinson's. I mean, they're always weaving and bobbing ;)

Mentaly handicapped? No they may not have the faculties to properly weigh the risks involved.

Physically handicapped, sure. If you are of sound mind and want to step in the ring that is your decision.

I see no compelling reason why not, so long as it is their decision.