Years ago matters less than the fact that it didnt even happen in the pro ranks. His kickboxing record will soon be held against him.
Vitali wasn't even legitemately KO'd in the amateur loss to Maskaev. It was just an injury or something, kind of like in the Lewis fight. Vitali does have a very good chin by all his accounts.
His right shoulder was injured and his trainer told him that if he uses his right he's gonna throw the towel. He did and the fight was stopped.