I can't understand why you're laying all this blame at MAB's door when it's clear that Nady fucked up big time. If it was a slip then you get between the two fighters dust the guy who slipped down and resume the fight. If it's a knock down then score it. He did neither.
I've seen it happen loads of times just as I've seen loads of fighters touch down, pop back up and get tagged again for their trouble, it happens.