Throwing your cards forward while facing a bet or raise is a fold. Unlike at showdown, there is no rule-based reason to suggest his hand is retrievable and therefore may be ruled live. Floor should explain that it is his responsibility to follow the action and protect his hand, and in the future he should not discard his winning hands until he is being pushed the pot if he wants to avoid situations like this again.
I am 100% certain you lost the hand and would have had no issue with the ruling if you had won, and would have been pissed if you had AA, and the guy is saying he wants to call it off allin pre and the floor didn't allow him to do so with his clearly identifiable hand.
Time to play mind games and say no if he wants to go all in then let him, then say nothing but laugh at his face. If he had a marginal hand he would fold but is he had a good hand and called so be it.
