was this handled correctly?

The only way a dealer should handle this is to immediately stop the action and call the floor.

If the floor had corrected the hand this way I wouldn't be to upset, but I if the floor called the hand dead I wouldn't be surprised.

Player throwing his cards in the muck that hard should get kicked in the nuts.

last night I had the problem occur that when the button was on seat 7, player UTG in seat 10 folded his cards by snapping them quickly out just in time to intermingle with the last card I was pitching to the button. There simply was no reason to do this since he was in seat 10 since folding from seat 10 doesn't require that you fling them.

The floor called the hand a misdeal, which only bothers me because it creates an incentive for UTG to try to do this if he doesn't like his hand.