You Make the Call

Floor people are to consider the best interest of the game and fairness as the top priority in the decision-making process. Unusual circumstances can, on occasion, dictate that the technical interpretation of the rules be ignored in the interest of fairness. The floorperson's decision is final.
--Rule No. 1, 2004 Tournament Directors Association Rules

Tournament situation. Player A is all-in. Player B is the only one to call. They expose A-4 and A-9 (suit unimportant). The board comes

7-7-T-8-2

and the dealer declares a chop. Neither player protests and both start to take their bets back. Just as the dealer reaches for their hole cards and begins to sweep up the board, an alert railbird says, "That's not a chop!" The dealer sweeps everything into the muck and straightens the deck as the railbird points out a second time that the hand should not have been chopped. Everyone stops and realizes that the hand shouldn't have been chopped, and the floor is called over.

The dealer explains that a chop was called but he believes the call was in error. The floor asks the losing player "Did you deserve a chop?", to which the losing player replies, "I don't remember." The dealer reconstructs the hand for the floor, and then the floor asks "When did you realize the chop was in error? After you had already mucked all the cards?" The dealer says yes.

You are the floor and need to make the call - does the chop stand, or should Player B win the hand?