Poker At showdown who can read the hands?

At showdown, all action complete, two players check on the river. The first player shows a straight. The second player lifts his hand up in the air so that three other players at the table can see it but not the entire table. The second player looks at the his hand for a few seconds and acts like he might fold. A third player at the table (but not in the hand) tells the second player that he has a flush.

Is the third player who read the second players hand at showdown violating a rule and what is the penalty? It's not properly tabled but not folded and there is no action left and the cards speak for themselves.




Robert's Rules of poker says

3. Any player, dealer, or floorperson who sees an incorrect amount of chips put into the pot, or an error about to be made in awarding a pot, has an ethical obligation to point out the error. Please help us keep mistakes of this nature to a minimum.


and

5. Any player who has been dealt in may request to see any hand that has been called, even if the opponent's hand or the winning hand has been mucked. However, this is a privilege that may be revoked if abused. If a player other than the pot winner asks to see a hand that has been folded, that hand is dead. If the winning player asks to see a losing player’s hand, both hands are live, and the best hand wins.


So this implies that if the second player had made a bet and the first player called it then the third player would have the right to see the hand (even though the second player was showing anyways) and according to paragraph 3 would have an ethical obligation to read the hand so the pot was given to the winning hand.

I know that some card rooms allow any player to ask to see any hand at showdown whether it was called or not.

I guess it also boils down to the definition of tabling a hand.

Source.