Unless there is videotape of OBL and Saddam together every day actively plotting 9/11, then the left will not be satisfied. Even then, they would claim the CIA dummied up the evidence.
Relationship or not, take the movie "Swordfish" and see this in reverse perspective. Any American terrorist group inside our borders may not have a relationship with our government, but if our government does nothing about it, then it's just as bad as having a relationship. Now if there was an American terrorist group that murdered people of the Middle East, our government would be blamed by every member of NATO. If only we could fight fire with fire just to prove a point...