So much for the "Ron Paul speaks his mind and is honest, unlike all the other filthy Washington politician liars!" defense.
In that case, he would have ticked off a lot of fans either way, for no good reason. While I admit that that is perhaps a flaw, it is a fairly minor one. And it is indeed possible that he is unsure.
The difference between Ron Paul and a normal politician is that Ron Paul is perfectly willing to tick off large groups of people if he actually has a valid reason to do so. Ron Paul isn't going to be quiet about his view on Israel, legalizing hard drugs, or the Patriot Act just because his stances are opposed by the vast majority of Republicans (Probably "And democrats" as well, but they don't necessarily matter quite as much because the only Democrats that would defect and vote for Ron Paul are the ones that agree with him on some or all of those controversial stances).
Most politicians that are running for President basically toe the party line on every issue and its really just a matter of how conservative or how liberal they are. Santorum is also a bit of an abnormality in that he quite openly admits (Not in so many words) that he's a theocrat and barely gives a crap about fiscal conservatism when compared to social conservatism. But since I don't care about Santroum whatsoever and would have likely supported Obama over him much as I did over Romney, I won't bother to pursue this line of thought any further. Discussing Ron Paul is much more interesting
Regardless, I do wish he had answered the question, but frankly, I can't honestly say I would have necessarily actually done so. It may have been noble, but its already noble to be willing to tick off so many people over things that actually matter.
Nobody's perfect either, not even Ron Paul. That doesn't mean that he isn't a heck of a lot more honest, forthright, and sensible than pretty much anyone else in Washington DC.
If he knows how to stop the attacks, why did 9/11 happen on his watch?
He wasn't the President. Bush was. Of course, Bush likely knew how as well, but unlike Ron Paul, would never actually do it if he had the authority.