I am about to go get my hands dirty so i dont have time to find a reference, but from what i have heard there were plenty of indications and chances the government had to stop this. Some elements also dont line up; building 7 was the crisis response command center, a steel framed building that fell at the speed of gravity without being hit by debris, theres buildings in Aleppo that looked like swiss chese from the fighting there and they didnt collapse like that, my guess is whoever was stage managing the thing was based in building 7 and wanted to make sure the evidence was destroyed.