Non-Interventionists believe we were attacked because of our meddling in the Middle East and other foreign adventures.
I agree with that. I just found it interesting that he didn't delve into it. Instead he seemed to dance around the topic, which is odd for him.
I myself would simplify what you said: either all the terrorists are totally nuts; or our government completely screwed up our foreign policy in the middle east. If it is the latter, as I believe, then everyone should really did into the question and fast -- in addition to bombing the crap out of them.
I would take choice "B". With a little bit of choice "A" mixed in. If we had followed the foreign policy of our Founding Fathers, I seriously doubt we would have been attacked. Friendship and trade with all who seek it, entangling alliances with none! How difficult is that for people to understand?