Well there used to images on the web of a charred body in a plane seat, but that was taken down. The damage was caused by a plane as the pieces of the aircraft were all over the lawn and inside the building, how do you indicate that the damage doesn't/can't be caused by a plane?
D'uh, keep up (with yankee logic)!
The fact that it "can't have been a plane" means that trucks were touring around the Penthouse lawn scattering plane debris. The rest was down to explosives and faked DNA evidence.
Simples.