So after boarding their only recourse is to offer increasing compensation until someone gets off.
The admission of wrongdoing came from the CEO:
>...Two days after the incident, Munoz issued an additional statement, apologizing and promising that such an incident would never again occur on a United aircraft. He said, "No one should ever be mistreated this way." In an ABC television interview, Munoz was asked, "Do you think [Dao] was at fault in any way?" Munoz responded, "No. He can't be. He was a paying passenger sitting on our seat in our aircraft."
https://en.wikipedia.org/wiki/United_Express_Flight_3411_inc...
Airport security might have followed orders but those orders couldn't have come by anyone but United.
"I don't know or care enough about the reason for arresting him, but that is still a procedure that must be followed."
"I don't know or care enough about the reason for preventing him from flying, but that is still a procedure that must be followed."
and so on. The reason matters because it determines if the procedure/request is ethical. An unethical procedure shouldn't be allowed to keep existing just because it already exists.
Refusing to leave is exactly what caused the problem to be fixed, taking it to courts would do little more than get the man a half-hearted apology and a bit of compensation.
Also, a half-hearted apology and a bit of compensation is all the fellow is entitled to in this situation.
This is someone that paid for a service, is following all the rules set in contract and is not causing any problem to you. You merely picked on this person at random.
This is like expelling a tenant that didn't do anything wrong and paid the rent because you want to let your cousin sleep for the night.
Also, evicting a tenant so you can occupy the space is pretty much the most legitimate reason there is for eviction.
And planes are nothing like private cars. An analogy would be Taxis. Taxis accepting the fare but then leaving passengers "at the side of the road" without provocation or reason is also against consumer laws in lots of jurisdictions.
https://www.transportation.gov/individuals/aviation-consumer...