I imagine the reasoning goes somewhat to the effect of: If a plane goes down, it's reasonable to expect that everyone on board will die. It's less reasonable t

I imagine the reasoning goes somewhat to the effect of: If a plane goes down, it's reasonable to expect that everyone on board will die. It's less reasonable to expect that the blast radius of a device that was sufficient to down an aircraft would be sufficient to encompass an equivalent number of people in the security line.