I see this news as a loss of faith in the police. If the police are not trusted or not helping or making things worse then of course people will form their own gangs for protection. Citizen is trying to profit off that. Businesses and rich people do this all the time, this sounds like a service for less wealthy people of the same nature. It could help tame the police if independent observers with the power to intervene and wearing body cameras streaming to a remote server show up at incidents. In fact some people may specifically want protection from the police in situations where they think the police may react badly (e.g., trying to get help for someone with mental health problems). Goons for rent would be a bad way to implement this service. Observers and defenders and negotiators and de-escalators for hire would make more sense and have less liability for the company offering the service. This is the basic idea behind lawyers, you can not trust government to watch out for your interests so you hire an advocate to represent you and protect you. In fact, temporary legal representation during a sudden crisis is another service Citizen could offer. Calling a lawyer to be present during a crisis is something anyone can already do if they can afford it. Privatized police already exist (campus police, corporate police, security guards, even military mercenaries who do policing work). Hiring an observer/witness for cheap seems like a great new business model!

Private security forces are accountable to their customers before their shareholders. If I don't like how my private security company is behaving, I can cancel my contract and switch to another company. When enough contracts are cancelled, then these hypothetical shareholders get involved.

If I could cancel the "contract" with my local law enforcement agencies, I would have done that a long, long time ago.