Just for the sake of reality, the person just stole the weapon from a police car. That's not "legal open carry."
Just for the sake of discussion... Since when does the News Media's paid private security personnel have the right to disarm someone else with a firearm out on the street? If that was a legal open carry, that would appear to be felony armed robbery. Even if the goof ball stole the rifle from a cruiser, what makes the news media private security the arbiter of justice in the middle of a riot?