Status? Although he didn't show both YET, he still has a live hand, and the dealer shouldn't get involved.
I occasionally do this myself when playing, so let me describe this another way.
If I have a weak hand, such as one pair with a bad kicker, I'll show the card that makes the pair, but still hold the other card. If anyone else shows a better hand, I'll turn that card face down and fold. Once everyone else folds, I'll turn my other card up. If it gets to the point where it seems like I have the winner, but there's another player holding cards, waiting to see if I'll muck my kicker, then I'll turn it up without being prompted to do so.
I've also been the other guy, holding onto my losing hand, waiting to see if the 'winner' will muck his kicker. If the dealer tells that player to show the other card, I'll tell him, in no uncertain terms, that he shouldn't get involved when there is still action pending.
Note that I deal in a poker league. It's supposed to be a friendly league. If a player only shows one card, I will not ship the pot, even if all other players have folded. I'll say something like, "Show me a winner." Afterwards I'll explain how they could have lost the pot in a casino.