Okay, really?
If you are a air marshall- someone goes running down the aisle, claiming that he had a bomb, the person runs off the plane and onto the jet way, heading straight for the terminal where there are thousands of more innocent people inside- then......
What would you do? You get half a second to make a choice- you either let the guy run into the terminal full of even more people, even after he has already threatened people that he had a bomb or do you shoot the guy? Those are your choices.
Given the choices this air marshall had to make- I would have done the same thing- I would have shot the guy. The air marshall's job is to shoot the guy and protect as many people as he possible can.
You have had hours and hours to think about this and what you might have done differently- the air marshalls had half a second. They did their jobs and they did it well.
As terrible as it is that someone with some mental problems was shot and killed today, I feel safer knowing that air marshalls are on job- and when American lives are threatened- these air marshalls will risk their own lives to protect Americans.