DUmmies fear a right-wing religious take over in the US, but welcome a truly evil Islamic movement. 
The lefts enchantment with islamists is threefold I believe.
First,they view them as a comrade in arms to an extent,after all they hate American capitalism just as they do so how can it be all that bad.
Naturally they feel that as a gratitude for not impeding them they will be spared the horrors of an islamist state.
Second is that it shows the lefts world view as hopelessly failed,there is actual evil that needs to be defended against.
This means that resources (money) has to be used to that end and that means those dollars can`t be given to them.
Lastly is they have a common enemy in Israel.
Nothing infuriates the Godless hatred of the left more then the existence of a Jewish state and its Biblical implications.
The vast majority of the left would happily see Israel destroyed tomorrow.