Simply he did an experiment where he had absolutely no idea what he was doing; end of story. I cannot disprove an experiment that already fails on its own premise.
Let me emphasize again that this is old news
The assertion of the TM is that either the locations of the explosives are coordinated with the target floors the planes hit, or the explosives were planted on every floor. Watch any David Chandler video and he will cite every ejecta wave as a row of detonating explosives propagating the collapse. Other explanations they offer are that the explosives were planted inside the columns, protecting them somewhat from the heat until they were timing to go off. How exactly any of these scenarios are supposed to have been pulled off I have no idea. There was no physical evidence of this found, not even of damage to columns consistent with blast trauma, or for that matter - as truthers like to include - damage consistent with the melting of end connections in any of the buildings.
Absolutely not. Since the event has no precedent with an equivalent scale the results seen in this one are suspicious on the premise that a disaster of this scale happened for the first time in history. As long as it lacks a precisely equal precedent, it'll always be enough for truther's to try and wiggle the CD scenario in, no matter how proposterous their theories, or their claimed experiments have to be.