Not convinced, no substantial evidence whatsoever that it was an inside job.
A couple pages back there was a misconception that the steel structure had to melt to fail?: not the case, the structure weakened due to concentrated heat lowering the yield strength, fracture toughness and introduced thermal stresses. The plane itself plus the culmination of the already impacted floors results in much greater localised loading and the severing of much of the existing structure concentrated the existing loads (removing even a small percent of a supporting area can concentrate stresses much, much more). Once the structure in the area of the fire collapsed, the subsequent floors were at least ten times too weak to prevent further floor collapses. The building's architects claimed to have designed for impact (which it did) but their claim that it could withstand the ensuing fire to an already damaged structure were not true and not substantiated. This kind of prediction is not even possible with today's simulation models and computing power.