Someone walked into a Los Angeles Police Department station, a facility where nearly everyone is highly trained in gun usage and mentally prepared to use lethal force to end an encounter, and this would-be killer wasn't instantly disarmed by these people?
Sure, let's arm schoolteachers. And market managers. And bus drivers. And crossing guards. And mail carriers. And secretaries in law office lobbies. And greeters at Costco.
And why not kids?