"I'm not sure you can state as a fact - with absolute certainty - that OBL would have attacked us if we had not had troops in the Middle East. Can you cite a source?"
How many attacks did OBL's outfit do?
Hint: Plenty
How many of them had anything to do with Saudi Arabia?
Hint: None.
Yes, OBL would have attacked us anyway.
Saying that if we just pulled out of Saudi Arabia OBL would just leave us alone is fanciful thinking at best, and dangerously ignorant at worst.
No, I'm positing that had we never gone into SA in the first place, he would not have bothered us. But that is speculative, and we can never know for certain. And ya, it may be a bit of isolationist thinking peaking through.