Heh, alright, I can't stay here too long, I told my girlfriend I'd be over tonight, but I just wanted to touch on the kerosene deal.

First, there was a lot of the stuff, and it was burning inside the building. Second, although it takes a lot more heat to melt steel than kerosene can provide, if you heat steel to the temperatures they calculate it approached, it loses a lot of its strength. If just a few key beams yield, the weight from the floor above it causes it to collapse, pretty much like what happened on all the videos of the towers collapsing.

If there were bombs, the towers would have collapsed right after the explosions, but the kerosene had to burn for a while before the towers collapsed.