Extortion (also called blackmail, shakedown, outwresting, and exaction) is a criminal offence of unlawfully obtaining money, property, or services from a person, entity, or institution, through coercion.
Coercion ( /koʊˈɜrʃən/) is the practice of forcing another party to act in an involuntary manner (whether through action or inaction) by use of threats or intimidation or some other form of pressure or force.
The gun owner is not being forced to act in a "involuntary manner." He has the choice to take it or leave it. He has the option of leaving the bar and remaining free to move about in society until the police obtain a arrest warrant and capture him.
The bar owner could file a civil suit which will cost him money fo have a lawyer to sue the gun owner.
But why should he when he can call the police, file a criminal complaint and let the legal system bear the cost of prosecuting the gunowner?
The result is the gun owner now has a criminal arrest record (which alone may prevent him from getting some security sensitative jobs), take his chances with a public defender or hire a better one (which will cost $$$$) and if convicted, lose his ccw and right to own a firearm, lose his gun , pay court costs AND STILL have to pay the bar owner for the damages he caused.
And the bar owner still gets money for his damages back...
plea bargain - (criminal law) a negotiation in which the defendant agrees to enter a plea of guilty to a lesser charge and the prosecutor agrees to drop a more serious charge.
On the other hand his lawyer may be able to produce witnesses that he did not start the fight and was defending himself and win the case.
How in reality is it any different than what the bar owner is offering?