Yeah I get what you mean, but it’s not really about converting the cop into “your group.”
It’s about what your actions do to everyone watching, and what it does to you.
Plato makes the point that you don’t make a dog better by beating it. You just make it worse. Same with people. You’re not persuading, you’re escalating.
If the goal is change, you don’t have to be nice, but you do have to be effective!