On the one hand, I despise the UN as a bunch of power-hungry bureaucrats. But I personally knew a couple of Belgian UN peacekeepers on the Green Line in Cyprus who were good guys.

I think the emphasis on this is:
#1. The UN is naive in thinking that any of the Islamic nations respect the UN forces.
#2. This is a dangerous second front to be opened up against Israel.
#3. Israel can't count on any support - not even from its erstwhile greatest ally: the United States.