I had this happen to me the other day. Or at least a similar example.
In a four card Omaha pot, we have come to showdown and player 1 has asked player 2, "Have you got the top straight?"
He responds no, and shows

The board reads.

Player 1 then says, "You win."
However, he keeps his cards in his hands and after a pause just tosses them down onto the table.
I notice that, (having all landed face up) that he has

and announce that it is a split pot.
Player 2 was not impressed, however, I said that despite the fact that he said "You win.", his hand was tabled and the cards speak for themselves. In this situation, I think that despite his verbal passing and throwing down of cards, that they stand.