The whole "nuke Mecca" thing just looks completely mindless to me. If he'd have said something about nuking the capital of a cuontry found to have supported the terrorists who nuked us, I'd see the logic at least. It's a threat to governments to crack down. Okay, I'm with that.
But Mecca is just a place in the middle of the desert, and within the control of only one ME government. Not much of a deterrent to the rest of them.