Was Kimbo a martial artist or did he have any real training at all during his street fighting days? I don't think so. We're not just talking about untrained street fighters who don't have sport fighting records, but trained martial artists who don't have such records yet are still fighters. If Bruce Lee had verifiable street fights it wouldn't put him and Kimbo in the same class. You can't say Bruce Lee was untrained.
Besides, the thing is you were saying Bruce Lee was an actor and not a fighter at all, based on the fact that he had no official record. So are you also saying Kimbo wasn't a fighter, even though he has verifiable street fights, just because it wasn't against trained opponents in an official setting? He may not have been a good fighter, because he was untrained, but he fought. Therefore he was a fighter.
Now someone like Bruce Lee was obviously well trained and highly skilled. But he's not a fighter because... he wasn't a sport fighting athlete and there's no footage of his street fights?