Right they meet even violent offenders with "physical restraint" so long as they are not met with violence. And "physical restraint" is little more than asking a person to turn around and cuffing them, and in some cases - that's not even involved.
We could discuss the ethics of imprisonment, and I expect we'd agree. But you certainly can't claim that police's task is to deal out violence - particularly preemptive.
You have a funny concept of violence if abduction and imprisonment under threat of physical force don't count. I guess the robber that steals at knifepoint is also non-violent if he doesn't actually plunge it when the victim complies?
We could discuss the ethics of imprisonment, and I expect we'd agree. But you certainly can't claim that police's task is to deal out violence - particularly preemptive.