It has done with a passenger exhibiting odd behaviour leading to the flight attendant believing that he might cause a disturbance during the flight. People causing problems on planes are a nightmare for airline carriers as it can result in early landings, increased risk of life threatening incidents and subsequent scheduling problems.
When it comes to planes better to be safe than sorry.
It has everything to do with 9/11, and the subsequent 'promotion' of flight attendants to security guards. If you doubt that, then just try to imagine the same scenario happening in year 2000...it would not have happened. This is also related to human psychology, as shown in the now classic Stanford Prison Experiment.
It has done with a passenger exhibiting odd behaviour leading to the flight attendant believing that he might cause a disturbance during the flight. People causing problems on planes are a nightmare for airline carriers as it can result in early landings, increased risk of life threatening incidents and subsequent scheduling problems.
When it comes to planes better to be safe than sorry.