A fully understanding of what happened to the Word Trade Center buildings is not going to come without a proper investigation. At the current time, that is all the professional engineers who have looked at the collapse are asking for.
NIST says that WTC7 experienced a progressive collapse due to fire induced thermal expansion. There are many reasons why we can be sure that their hypothesis is wrong. That is enough reason for a proper investigation.
There are all kinds of allegations being made, and a hell of a lot of misinformation. Sorting all this out is never going to be easy. I do not want to speculate on what the final outcome of any investigation might be. The fact that NIST produced a bogus report on the collapse of Word Trade Center 7 is enough to justify a proper investigation (as recently requested by New York first responders among others).