Dealer Messed Up - WWYD?

Playing 2/2 PLO in local room.

Dealer is a regular dealer that has been dealing since I have started playing poker in the NH rooms ~ 2010ish. Guy is usually funny, but can be an airhead make mistakes, seems like he is just a space cadet.

Anyway on to the situation -

Player A and Player B are all-in on the turn - dealer drops the stub, spreads the remaining deck out, essentially into the muck, asks players to reveal their cards. Players state that the river has not been dealt yet, dealer collects the spread out deck, deals the card. Player A complains immediately, floor comes over, floor states the dealers actions stand.

Should the dealer get spoken too? Players should have obviously made a stink before dealer picked up stub? Dealer definetly knew he was in the wrong and expressed to the floor that he did everything by the book, and that the stub never was intertwined with the muck.