Opinions on a Floor ruling

[PanchoVilla]

20-40 game at Bay101 Sunday night. Excellent game. Seat 3 is a LAG player and Seat 10 is a loose calling station.
Play gets to the river and the board is 9-7-x-x-x. Seat 3 bets out and is called by seat 10. Seat 3 says "You win" and turns over his 7-6. Seat 10 shows one card, a 9 and then tosses his other card facedown towards the muck. The card actually just touches the muck.
Seat 3 now says isn't that a dead hand? I want to know the rule. Seat 10 immediately grabs his facedown card, which was an 8 and turns it over and starts telling the other player how much he sucks, etc. He is bitching about how thats not how they do it at foxwoods. (like that matters at Bay 101)
The floor comes and calls for the camera and the rack up the pot while they wait. It takes about 15 mins and he comes back and awards the pot to seat 10 saying the ONLY reason he is getting the pot is because the other player said you win, otherwise his hand would be dead.

If you agree with the decision what if the player said "You have to have me beat" or "I missed" instead?

I guess the lesson is never say "You win". I am 90% sure that even if he had not said you win Seat 10 probably would have done the same thing. He never bothered to protect his hand sitting in the 10 seat even after one player mentioned it like 300 times.

Also for the dealer. Should he have swept the discarded card fully into the muck once it had touched it? I was wondering what they should do there.

Marcus