Thermite was found in the dust and you can literally see the cutting charges go off in the footage.
I don't see why it couldn't have been a combination of techniques. Thermite or detonators might react to Hutchison effects in a way that obviated the need to wire all the detonators together. A neutron bomb placed way down below the basement sub-floors could have helped weaken the structure and help account for such pulverization. There were probably backup plans in case the detonators didn't go off as needed.
I don't see why it couldn't have been a combination of techniques. Thermite or detonators might react to Hutchison effects in a way that obviated the need to wire all the detonators together. A neutron bomb placed way down below the basement sub-floors could have helped weaken the structure and help account for such pulverization. There were probably backup plans in case the detonators didn't go off as needed.