The guys on the train didn't wait. The guys on the plane didn't wait. But, in this case it seems that they were all told to lay on the floor before they were questioned. We haven't heard all of the story yet, probably not even the correct details.

Monday morning quarterbacking is only good for preparation for a possible future confrontation. Being oblivious to your surroundings doesn't prepare you for possible exigent circumstances. Being prepared for a building fire is called thinking ahead. Being prepared for an assault is also thinking ahead today. It's not IF it can happen, but WHEN it will happen to you.