I knew nothing about tannerite until today. A FR member posted about it on that thread (the 50 pounds being found) and indicated it could be set off by a bullet striking it.
Likely the vehicle (his) was to be parked somewhere and be part of the chaos.
I’m guessing the police are also just trying to figure things out too. With all the stuff left in the car, and perhaps in a spot where he couldn’t shoot it from his room - that might indicate he was hoping to get back to it to escape.
Or, the idea of others that failed their tasks.
I found it odd, before knowing about any explosives, that he didn’t rig a bomb at the door to his room - kill himself and whatever cops outside that he could see with his cameras. It is even more perplexing now that I know he had a bunch in his car.
Although I know with me, if I have to make more than two or three trips into the hotel room I get pretty lazy. ;)