There’s no contradiction between abusing you wrote and police being violence workers. Police cannot do their jobs without resort to the threat of violence and occasionally actual violence. The degree of restraint varies wildly between different forces but that does not. When traffic wardens, paramedics, social workers or firefighters need someone to do legal violence they don’t do it themselves, they call the police. They are one of the forces the state has delegated its monopoly on the legitimate use of force to, along with the military. They are not primarily in the business of violence, like the military, but they can’t do their jobs without the capacity to be violent either.