now that I understand kin's one I still think it's a horrible ruling. if you rule the hand dead then you are saying that deliberately exposing your hand is the same as folding. you can't give people penalties for folding
assuming the house rule is that you cannot show your hand then either it's a fold and you have no penalty or the hand is still live and you give a penalty after the hand for exposing cards but not a combination
if there were more than 2 players in the hand then ruling it as a fold and giving a penalty is acceptable as you're affecting the future action in the hand
This I like and hadn't really thought of.