If there was molten stuff that long afterwards then who knows. No bomb, detonator, fuel or what-have-you would manage to keep contrete and steel glowing for that long without a source of energy.
So where did this energy come from? Was the debris plugged into the mains, or have they found a way to slow cooling, contravening Newtons laws of cooling?
I think the people that think of these theories are very very clever. they work so hard to turn normal images into 'scientific' fact, often with quite believable reasoning. But they remain, in my opinion, idiots.
Off Topic: The amount of nonsense that gets quoted or linked to in these debates (these being this one, the religious ones, and that sort of thing) demonstrates that some people must spend all their time looking for a form of truth that appeals to them and not enough time leading their own lives! I don't have time to read 99% of the articles quoted, let alone read hundreds of them to work out which ones are credible (although I reckon most don't read others, they read one and quote it to others as the truth, claiming it as research). Why give a shit about if some officials somewhere conspired to make a random building fall over to kill some foreigners (when they could have just shouted "God says kill those wearing towels") if you have to waste your life reading about it? Move on. Make a cake. Run a marathon. Race a car. Read a classical novel. Teach yourself carpentry. Watch brainless TV quiz shows if you must.
Oh, by the way, fracture and failure of ferrite components (indeed, most metals) tends to take on uniform, almost fake looking angles. I see nothing suspect about the clean breaks in the metal structure, nor the appearence of something molten on the edge of that break - it could be plastic for a chair that happened to be near by at the time... Why does a clean break (perhaps even a designed in breakage point to control parallel collapse in the event of earthquakes, terrorism etc rather than toppling) have to mean alien technology (which is that that rate of cooling must be).