Let's say that you win in every possible situation except the other player having exactly the Ace of Spades. If they show you one of their cards is a 10 of Hearts, does that change the odds of them having that Ace?
My thinking here is that you already knew that at least one of their cards was not an Ace of Spades, so you aren't gaining any information by them showing you what one card is. They aren't randomly picking a card to show you, they are purposefully showing a card that is not an Ace of Spades, and no matter what hand they had, they always had a card that was not that Ace.