Bush says it's wrong to hold bilateral talks with Kim Jong Il, because that's exactly what he wants.[1] He said, "When you're talking with a madman, you want to be surrounded by allies." Like China. Allies.
So when talking to a madman, you want to make sure you're surrounded by allies. But when invading a country with the world's fourth largest army to depose a madman ... eh, we'll do that one on our own.
[1] Let's ignore for the moment the possibility that what Kim Jong Il wants just may also be good for us.