I wonder if his car was supposed to blow up as an escape diversion, but it didn’t.
He was supposed to blow up his car and the jet fuel tanks at the airport. Could’ve been one hell of a mess. He was not only nuts he was evil nuts.
Did he park it near those jet fuel tanks?
Today I read that he'd put a few holes in some fuel storage tanks on the other side of the concert area. There was no resulting fire or explosion. And, it's not clear if those were intentional shots or the outer area of the spray and pray. But, if his car was anywhere near there, it would fit in with your suggestion.
50 pounds of tannerite would indeed suggest such a plan.
CC
I would think the car was supposed explode with the arrival of first responders to the concert to treat the injured.
His car was parked around the other side of the building in the Mandalay parking lot.