If its captain's orders however, then the captain of the airplane should have every right to remove a passenger.
He doesn't have the right to because the airline wanted them off in breach of the contract of sale and the guy said "yeah no".
Refusing peacefully to go along with the fiction the airline has created isn't causing a disturbance. You can't force someone in to a "disturbance" state if they're just sitting there。
That said, the captain's decision does not make him immune to lawsuits, disciplinary action, etc. but on his plane, especially while flying, temporarily he IS god.
If you want to sue afterwards you are allowed in America to do so. But the captain should be allowed to call police in to remove anybody. Period.