In states like NY though they can have a considerably easier time getting carry permits since they can argue it’s with cause better than a random private citizen.
Also the obvious thing to do is offer your services for free to judges and prosecutors. The dark cyberpunk future is on its way and inevitable barring a total collapse.
I was walking in Las Vegas and private security started following me in a vehicle. I ignored them and kept walking. They followed me for several blocks, driving very slowly right behind, and occasionally severing at me. I recorded them and called 911. The police showed up right away. The police had a long chat with the private security about public spaces and intimidation.
There's no law against paying intimidating people to stand in a particular place. That's what clubs do with bouncers.
And they have no more authority to use violence than any other citizen.