I don't think you should even be able to decline an auto-match. It shouldn't even show you the cards, it should just put you in the game. If you then want to quit because you don't like the cards, you should eat the loss. When you're clicking auto-match, you are basically saying "Instead of choosing my cards and opponent, I want a random game against a random opponent," you shouldn't be going on to say "...except I don't want to play against that guy, or that card, or that card."
I play automatch all the time, and I will play any card set, with anyone that pops up, even if they are unregistered. It's really annoying when I get declined several games in a row.