There is probably some truth to what he's saying. I can't find the article now (will post if I do) but it listed six (I think, might be five) reasons for why Osama Bin Ladin administered the 9/11 attacks. All of them were quotes and not just hypothetical and none of them had to do with RADICAL ISLAM~! All of it had to do with America's foreign policy and such, such as the occupation of the Arabian Peninsula for one.
Plus, he wasn't saying that if HE was President that it would have been prevented. He was saying that if people LIKE him were in charge and followed a non-interventionist foreign policy then 9/11 could have been prevented. Granted places like Iran have had bad feelings against America since the 50s, but if people like Ron Paul had been in power since the Reagan Administration, 9/11 could very well have been prevented.
Granted we are discussing a huge hypothetical, but it is still a potentially valid point.