Maybe Karate Combat rules are allowing on eyed fighters 
His story about his eye is very interesting, I listened him once and he confirmed that he had to bribe some people to give him clearance to fight as healthy.
Big balls are needed for him to do that, entering in octagon is one step closer to death or hospital, with one eye it is worse.
(...)
Damn, looks like he's serious about it isn't he? Unless there's more to that clip in which he takes it back.
I didn't expect that. He's one a few retired fighters who managed to build a successful career post-retirement, and iirc he has said in the past that he's retired for good.
I don't think KC pays that well, so it's probably not money-motivated and he's just missing fighting.
I have my doubts if his family would support his come back, given the one eye thing and all that.