“The guy wanted to go out with a bang.”
My biggest question about the entire thing is whether he killed himself after starting the timers, or just waited to die in the explosion.
Theoretically, like they do it in the movies, the cops could have just shot the guy full of holes right through the tin walls, gone in and defused the bomb with one second to spare, yay!
Nah, they stood around until it went off.
I suspect he triggered the bomb personally. He obviously intended no one to get hurt and the only way he could be sure was to set it off when he could look around and be confident no one was in the kill zone.
No alternate method of suicide could have been more painless or more sure, in any case.