Awww, you're disqualified. You ignored the word "reasonable".
Wow. Popular Mechanics. Yeah, they left no stone unturned. That article ignores the squibs going up the side of the building, brushes aside the video footage of explosions immediately preceding the collapse, leaves out Silverstein's "pull it" comment (oh, sure he meant "pull the firefighters") and, here's the kicker, "Our current working hypothesis is". Translation: They don't know either.
Now, with respect to their unwillingness to be too certain about their conclusions: That is reasonableness. They have rubble to go through. They have to draw conclusions based on the best available evidence. Unlike the conspiracy theorists, they cannot simply assert an hypothesis and ask the rest of the world to prove them wrong with metaphysical certainty. That's the easiest thing in the world to do.
Translation: They don't know either.
And neither do you. (Although you seem to be quite certain about your conclusions.) But the PM guys have actual evidence. And facts. And I will go with that.