Police response times will never be low enough to be physically preventative outside of special areas (airports, stadiums, high traffic areas). It doesn't take that long to mug somebody.

Police violence is more of a way to discourage wrongdoing on the part of rational actors. Irrational actors (terrorists, mentally ill, drug-addled, enraged, desperate) probably won't be affected short of an oppressive police state.

Police has no requirement to protect. Also, there are people who live in areas where the police response time is 1+ hours even for the most drastic issues.

Just like with encryption, it might be the state actors you want to be protected from. So that argument is totally nosense.

If you buy that argument you could also argue that govermnets should be trusted as a holder of cryptogrphic keys.