The truth of the matter is likely that Kerry knows there will be enough votes for cloture. His base will stay loyal to him, because he can say that he is in favor of a filibuster, when he knows that it won't happen. It's actually a no-lose position for him.
Except that he looks like a total idiot! Even the moron.orgers and DUmmies and KOSmonauts are going to see right through this phony stunt. What a jackass.