At the range nearly all casual police interactions like traffic stop happen happen at (<20ft), a knife has to be treated just as deadly as a gun. So even if you remove the guns you'll still have to treat everyone as a deadly threat under such a model.

20 feet is approximately the distance a person can rush forward, and have a decent chance of engaging in a weapon retention challenge.

its also the effective range for most people snap drawing a pistol in a use of force situation.