rules?

had a situation arise in a tournament game at the time declared the hand dead but later looked for a correct answer. During a tournament A player got up out of respect to smoke a ciggarette during the game a player who's wife was still in the tournament showed her husband her hand and at that moment the player turned around and saw her cards. The play was three handed and she was first to act and made the call he was the sb and made the statement that he had seen her cards he made the call and the bb who was now at a disadvantage checked. At that point it seemed unfair to the bb the small blind was being honest and could have said nothing. It would have been one thing if the player who had seen the cards had been in his seat. I had no house rules for something like this. At first thought was to make the sb hand dead for not being in his seat even though he was doing so out of respect to the other players as he was smoking. What do you think about this, is there a rule.