This whole sorry incident smacks of "last minute decision making". The place to deny boarding is at the gate. The crew should have already been on board and sitting in their seats - or the seats blocked off at least. Once passengers are on board it is too late and the crew should have been carried on another aircraft. Why were the crew in the wrong place? That is somebody's fault. Who decided to pick four passengers randomly and tell them to deplane? They nearly got away with it because the other three got off. That is somebody's fault too. This will cost United a huge amount of money in damages and share price. So it should. Talk about a sledgehammer to crack a nut. Should the CEO resign? Absolutely!