And that's the problem: the situation with UAL should be its own situation that is getting resolved in any number of ways, and should be. It is NOT and should not be, open season to go full-on disrespectful of airline employees at every turn and for every perceived wrong of any kind.
Hence why I agree with Roger Roger, self defense during a physical attack by a pax to a crewmember not only just for the crewmember's safety, but to also send a message. A message that the airline should back its employees with that certain actions are not ok, and will not be tolerated. Want a passengers bill of rights? Then there will be a crew bill of rights also.