Your opinions? ...
Hello Guillaume, here is my opinion.
So, assuming that the scenario is similar to this: Blinds are 100 and 200. Preflop, Alice opens for 1,000 and gets four callers, Bob, Carol, Don, and Erin. The pot is 5,300. On the flop, Alice bets 10,000. Bob, exposes his hand and folds. Carol raises to 35,000. Before acting, Don says: “I saw Bob’s hand.” The floor is called for a decision before Don and Erin are to act on the flop. The pot is now 50,300.
We can assume that Alice did not see Bob’s hand before she made her bet. Carol acted after Bob folded and she may or may not have seen Bob’s hand. Don told us he saw Bob’s hand and he has yet to act. Also, Erin may or may not have seen Bob’s hand and will act after Don. Both, Carol and Erin may or may not tell us the truth when asked if they saw Bob’s hand.
In this scenario, my ruling would be: Show Bob’s hand to all players and allow the hand to continue, having now given equal information to all. Alice should realize that the Carol may or may not have seen Bob's hand when she made her raise. Alice and Carol also know that Bob and Erin are going to act after seeing Bob’s hand.
Regardless of Bob’s two cards and regardless of the three flop cards, everyone is now proceeding with equal information. I don’t want to begin an endless discussion here on speculation of various boards, holdings, influences, and outcomes - to no avail. However, the players must take all of that into consideration as they proceed.
Finally, if there were reason to suspect cheating (collusion) my ruling would be different. Including, killing the hand, returning all bets, and disqualifying players.
Regards,
B~