I am amazed the American left does not see this.
The grip of Bush Derangement Syndrome is so strong that lefties can't help but have a twinkle in their eye for anybody else that shares their hatred. The fact that their Islamist brethren want them dead just as much as the want Bush dead doesn't concern them. This is not about policy, or ideology. It is about a mutual hatred, nothing else.
Horowitz addresses this in "Unholy Alliance." By the whacked logic of the left, the US alone stands in the way of world socialism. It is therefore moral to defeat the US, and by extension to help the muzzies do so. As for the caliphate the far left believes the muzzies will embrace world socialism rather than execute the perverts. Yeah, nuts.