I am not a big fan of the militarization of the police either, but SWAT teams do have their place, and a someone in a school with a gun is clearly such a situation.
Dad says he didn't have a real gun? How the hell would he know? How does he know the kid didn't get a gun somewhere else? Steal it out of the neighbor's nightstand? Suck cocks for cash until he had enough to buy a stolen gun from the crackhead that hangs out behind 7-11? Klebold and Harris's parents didn't know they had guns.
As to the other kid, it really comes down to how credible the police considered him. Even so, if you point a gun (even a fake gun) at a cop who is pointing a real gun at you, expect to be shot.
BTW, one of these is the "toy" the dead kid had, the other one is a real Beretta 92.
Tom