As I've said elsewhere, I see the reason for the sympathy of liberals for terrorists is their mutual hate of capitalism and all things associated with freedom. This is due to their not having any common sense, and by Jeff Head's comments we can see that it's mostly attributable to their immaturity.
Regardless, it's the classic case of appeasing the crocodile. They're still going to be eaten.
IMO liberals actually sympathize and like terrorists. They’re just too chickenshit to act that way themselves.