Under most circumstances, you really shouldnt lay the blame on the airline in situations like this. ALL airlines over-book their flights, and are permitted to do so under Federal airline regulations. They do so because some number of passengers are no-shows for a variety of reasons, and the seats would otherwise end up empty.
Whether you realize it or not, you agree to a whole host of things in the fine-print every time you purchase an airline ticket. One of those things is your express agreement to comply with and be subject to the airlines bump policy.
In practice, when there are more passengers than seats, airlines will routinely offer some sort of concessions to anyone willing to volunteer to give up their seat. These are often vouchers for some amount off of future travel - $100, $200, etc., plus guaranteed no-bump seating on the next flight to your destination.
When not enough passengers volunteer, airlines then select passengers to be bumped. Sometimes this is random, sometimes its based on frequent-flyer status with the airline, whatever. The point is, the plane isnt leaving with more passengers than seats, and someone has to get off - voluntarily or not.
Clearly this passenger objected to being involuntarily bumped, and I suspect the LEOs were called only after he refused the airline employees requests to depart the plane. I dont feel sorry for him at all, as disobeying a lawful order from an airline employee is grounds for removal. At the risk of stereotyping, it seems it could be a Doctor with an ego. (Do you know the difference between God and a Doctor? God doesnt think hes a Doctor.)
Where I think United is in the wrong on this is that the article indicates the involuntary bump was being sought to accommodate AIRLINE EMPLOYEEs flying stand-by. Stand-by seating is only to be granted when an open seat exists. It should NEVER be granted through the voluntary or involuntary removal of paying passenger.
Under most circumstances, you really shouldnt lay the blame on the airline in situations like this.
I should obviously black list this particular airline, since others don’t make such a mess.