If the floor is making this ruling, I think they should be doubling the pot to make both players whole.
I mean I can see your point, with a street of action yet, just because one player has top set doesn't necessarily means he's going to showdown and winning. Not something I considered in my earlier reply.
Chopping the pot does make both players whole. Each player gives up his claim to his money as soon as he bets it, and has no further claim to it until he tables the winning hand at the showdown or all other hands are killed - other than the shared claim to the pot that all live players have pending the eventual allocation to a winner, which in this case didn't happen.
The house cannot add money to the pot; that would compromise the integrity of the game. The house can only fulfill its obligation to ensure that the pot is allocated among the players according to the rules of the game.
The house can give any player they wish compensation for doing a poor job of running the game (since that is what the players have agreed to pay them for), but that has to be done outside the context of the game itself. Hence, comps, rather than just throwing money on the table.
IMHO. Based on the fundamental ideas at work in a game of poker, much of which boils down to "whose money is this?" and "according to whom?"
But still just because the stub is dropped and mixed, doesn't mean the floor isn't without a remedy to continue the hand. Even if you can't find the "correct" river according to "sacred-order-of-the-cards," it's within the floor's pervue to make the best stub possible, and in fairness, if both players are still holding their hands, all cards in the stub are unseen by each of them, so shuffling a new stub to burn an turn a river if necessary maintains all randomness.
I agree with you about the order of the stub not being sacred. I have greater concerns about shuffling cards that have been in play and seen by players back into the stub, even if they haven't been seen by the remaining live players. Still, it's not unprecedented - there are some mixed games where, if the deck is going to run out, discards and folded hands can be reshuffled (not sure if this ever happens in casinos though, maybe this is a practice in home games only?). So I guess I reluctantly agree with you that it would have been not unreasonable for the floor to decide the stub could be made good and to continue dealing the hand.
I think it's also not unreasonable for them to rule as I suggested, though.