We recently had a nearly identical situation in my agency. The guy's mother thought we didn't have to shoot her son dead. Unfortunately, we only hit him once but it was an immediately fatal round, the man was shot with a shotgun slug that went under his left arm, went through both lungs, severed his spinal cord and exited under his right arm. A pretty stiff penalty for the behavior associated with mental illness. For what it's worth, to read the story it's here:
http://www.greatfallstribune.com/app...512060303/1002
The mother is mad at US because her son did something that made these two agents afraid for their safety and they were forced to act to defend themselves. This is what I am afraid for for this Air Marshal, but it appears that people understand that, sometimes, we are left with no choice because we are NOT trained to recognize and deal with mentally ill people in less than one second.