The cop could simply have been doing his job, establishing a perimeter and making sure nobody was in the kill zone.

They had warning from the loudspeaker playing, so the cops should have been doing their normal response to a bomb threat.

The car absolutely was not the source of the blast. The blast came from the truck which appears to be parked on the left side of that road.

I agree that it is probably a Deep State OP to destroy a server in the AT&T building with damning evidence, but that cop had nothing to do with it.