What's the more reasonable explanation: he thinks there is no evidence that WTC 7 went down, or he thinks there's no evidence that there is a conspiracy. Speaking is different than writing; were he writing he'd probably make it clear what he meant. But we do this all the time when speaking, particularly in a situation like a Q&A.
If you believe he thought WTC 7 didn't go down, then I think that's what you want to believe. Much as, say, Seeker wanted to believe malice on your part back when you lost mod privileges despite the reasonable explanation I provided (accidentally hit edit instead of quote).