Uhm, lots to unpack here, but I think you are mixing things up. Yes, classic conservatives do a divide like that and there is a reasonable argument to be had about the existence of people “bad” people without getting into moral arguments.

But the libertarians do not make this argument. They literally argue that being bad, i.e. acting purely selfish becomes a net positive to society through the invisible hand of the market 🙄

If they support police than that is on the grounds of in-group thinking (“these are our guys”) or more often purely utilitarian as in: “we pay them to protect our interests”.