If one assumes that the conspiracy theorists are correct and the government was responsible for September the 11th and thermobaric type weapons were used then presumably the individuals setting the bomb would have been supplied with one sufficiently big for the task. As thermobaric type weapons are available in both large and small sizes it is presumably possible to make a medium sized one, assuming that a suitable one isn't already available. Of course it is virtually certain that the government had nothing to do with the 9/11 attacks and even if they did then using anything that wasn't supposed to be on the planes or in the WTC would be just plain stupid, and therefor any FAE was most likely due to the jet fuel being sprayed around and ignited by the impact.

BTW here is an unmangled link to the page referanced by the OP in case anyone should have an urge to read it (tinyURL.com is handy for getting around filtered words in a URL)