I think you need to take a look at the flight crew's capacity to make these judgements. When the passengers have already passed through greatly increased security, what is the justification for their conclusions?

Naturally, if there is a justifiable risk, then the passenger should be removed. If, however, they unjustifiably remove a passenger, then that's fine as well. It should be noted though that, if the aircrew have unjustifiably removed a passenger, they should then face disciplinary action for their folly.

If the aircrew are incapable of making that judgement, then they should either be made capable or refrain from making ill conceived judegements.

Things will start to settle down once the airlines and aircrews are made accountable for their actions.