The law says you have to follow the orders of the captain, and that the captain has the right to remove you for safety purposes. An argument like this would be classed a potential safety issue.

https://www.govinfo.gov/content/pkg/USCODE-2011-title49/html...

"Potential safety" is such a convenient backdoor!

When looking for the reasons behind the growing prevalence of security concerns in modern society (both from governments and companies), one can hardly avoid the conclusion that it's just the perfect justification for anything.

Sure it is, but that’s the law. Write your representatives to get it changed.

The way the passenger was removed was wrong, and potentially illegal (I assume you can’t shoot someone because they are trespassing on your property, presumably you can’t injure them either). I believe United paid some hush money to stop him suing, but I see nothing to show the captain wasn’t allowed to have him removed.

What happened may or may not have been legal (I would guess all involved parties, including the passive bystanders, did something illegal at some point); I believe the discussion is more about how badly the situation has been handled by the company, and consequently: can we trust those companies to operate an extra-judiciary blacklist of passengers?

It was not a safety reason. It's a financial reason. Any captain abuses the "safety" power should be de-licensed as a pilot.