I also hold the pilot responsible. It was the pilot who made the decision to deplane the passenger and presumably also the pilot communicated with ground staff to tell them to have the passenger removed by police rather than having a GA come on board to kick the guy off. It's the pilot's fault for believing whatever the FA told him and failing to communicate either with the passenger being removed or with other witnesses before making the decision to remove the customer and allow the FA to continue to work that flight. The ground staff who willingly called the police to intervene in this situation should also be disciplined for overreacting and not questioning what had happened. If there was a station manager involved, that person should have pulled the FA from the flight, even if doing so required returning to the gate yet again.

This easily could have turned into a Dr Dao incident with the cops severely injuring the customer.