Well I found this from Robert's Rules (
http://www.homepokertourney.com/rule...%20TOURNAMENTS):
21. Showing cards from a live hand during the action injures the rights of other players still competing in an event, who wish to see contestants eliminated. A player in a multihanded pot may not show any cards during a deal. Heads-up, a player may not show any cards unless the event has only two remaining players, or is winner-take-all. If a player deliberately shows a card, the player may be penalized (but his hand will not be ruled dead). Verbally stating one’s hand during the play may be penalized.
Looks like the SB should be penalized but the hand not ruled dead? I was the house in this case and we have never had a player deliberatly expose his cards before in 8 months of weekly tournies.