It's hard to say what factors led to the decision to evaluate this hypothesis. In a way, I suppose, it's good science since the study for WTC-7 has yet to reach a point where one can be definitively chosen over others. The conspiracy hypothesists offer explosives were planted by the US government as a political argument when in fact the antecedent is a falsifiable claim.

It doesn't take a PhD to read where this particular study is headed. For the demolition hypothesis to prove true (or more correctly - for it not to be proved false) the posited explosives would have to had create an overpressure that would have cause the windows to fail and would have created detectable sound waves. If you've ever been to an implosion (of felt a mortar blast for that meter) you can both feel and hear the explosion. It may sound like bias at first glance but it is not. The way a hypothesis is eliminated is by matching the observations expected by that scenario with what (in this case) was actually observed.

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In the progress of this discussion I shall endeavor to give a satisfactory answer to all the objections which shall have made their appearance, that may seem to have any claim to your attention.

Alexander Hamilton, Federalist No. 1