To answer the question, the pic I posted above ... is from the Rachel Corrie Foundation website, which gives you some idea of what prompts his slobbery rant.
I think the motivation is two-fold. The smaller part is driven by antisemitism, and the larger part by some short-sighted and ill-considered opinions centered on "being mean to underdogs."
In the case of Israel, I seriously believe that liberals are so uncomfortable with the idea that the Israelis are devoted to agressive self-defense, and so married to the idea that they're being "mean" to the Palestinians, that they'll do anything to justify the horrors committed by the Palestinians.
I seriously doubt that they have consciously evil intent; they're just so monumentally stupid, naive, and ideologically constipated that the consequences of their actions are undeniably evil. I suppose that makes them even more dangerous....
Its interesting to note that on a personal level liberal Hollywood has a dramatic increase of security personnel/bodyguards of former Israeli military personnel. (I gooogled it here: http://feeds.bignewsnetwork.com/?sid=307824). Liberal hypocrisy ?..