Well, he also states that he hasn't really spent any time analyzing the proof, so it's not like he knows that it's deeply flawed. Isn't Aaronson maintaining a bit of a bad-boy online persona? Could just be his way of saying what Bill Gasarch just wrote on his blog:

"So what are my uninformed views? If I was a betting man I would bet that it won't pan out. I would bet that he proved something very interesting, but not P ≠ NP. Why do I think this? This is NOT based on the author who seems to be a person to be taken seriously. Its just that the problem is so hard and we've made no progress on it since... . Hmmm, when is the last time we made progress on it?"