As a 777 captain for an Asian airline I can't imagine how the captain allowed this to happen on his aircraft to his passengers. I'm sure United has procedures that guide him or her to stay out of pax issues and that ground staff are in charge until the doors are closed but I can't imagine how he respects himself allowing these thugs to board his ship and abuse a paying customer that pays his salary. I'm thoroughly disgusted and happy I chose not to work for a US airline. The CEO's non apollogy shows the lack of leadership from above and I hope they are raped in the civil courts and I would love the CEO to be forced into resignation. Even if the pax was defiant he is owed a duty of care and he was reasonable in being upset. Disgusting necessary occurrence. It absolutely could never happen on my jet. There are always options to violence when we're not talking about a disruptive pax who groped someone etc. United clearly has no value for it's pax who had trusted it with their care.