The Left believes that once the terrorists defeat "The Great Satan" and our Jewish "vassals", the Muslims will be so grateful for their help and support, and so awestruck by the Left's brilliance, that they will beg them to lead the new Islamic world order.
For all of their phony panic about George Bush being a politician with religious beliefs, they can’t conceive of an ideology (i.e. Islamic Fascism) that cannot distinguish between religion and politics.
I mean it. Their minds can’t comprehend the concept. For them, it’s like trying to think about what a fourth dimension would look like. We humans, who have lived our entire lives in three dimensions, wouldn't even know where to start thinking about what a fourth dimension would be like.
(Yes, I know that some have posited that time is the fourth dimension, or that, according to string theory, gravity may be a force that flows through many dimensions, which would explain why it is so weak in our dimension compared to the other forces. This is politics, not quantum mechanics!)
Other than "support the underdog at all costs", that is the only explanation that makes any sense. And, given the arrogance of the Left, it wouldn't surprise me that they would think that the Muslim extremists would worship them and give them their undying support for their help. It's pretty much the same thing that they've believed in every Leftist revolution that's ever occured: "The people will thank us for freeing them from the bondage of Capitalism!"
And, when it turns out that "the people" can't stand them, they start executing, torturing and imprisoning them.
Which would fit right in with the Muslims.