Finally registered after years of lurking to comment on this:
As someone who lives in a country where not even police carry firearms(excluding the AOS*), where deadly force is only to be used reactively as a last resort to protect life, I'm experiencing major culture shock reading this. Especially as we are talking about a Bouncer aka Security Officer aka Private citizen, the idea of deadly force even being on the table caught me off guard.
It's not, really. If anyone in private security uses deadly force against someone who is not threatening lives with deadly force, that private security person is going to jail. If someone dies as a result, they face murder charges and if the jury does not agree that the use of deadly force was required in the situation, they could go to jail for a very long time. In theory this also applies to police, but in practice police are often acquitted at trial due to the nature of their job when private citizens (including security employees) would not be. As a private security worker, Elliot might occasionally do someone a serious injury - but if so, and that person chooses to press charges, he will find himself on trial.
As far as the law is concerned in the USA, you ought to be completely safe w/r/t licit use of deadly force in any public space ... until the moment you pick up a weapon and threaten someone's life, or perform some form of physical assault that poses a risk of death to someone.
Also, while the ownership and use of firearms is a legal right for American citizens, most of us do not own or use them. In most urban areas, actually carrying a firearm is prohibited, so owning them means keeping them at home and perhaps taking them out to a firing range or hunting occasionally, but if you have one on the street you will get arrested. I grew up in an area where firearms are tools for hunting, pest control and the defense of livestock from predators. We all got hunting licenses every year and had documents certifying that we'd been trained on gun safety. There were a dozen firearms in our house - different types for different purposes. But now I live in a city and have no use for them so I don't own any.