> We’ve just been informed that in threatening situations there is no time to chamber a round, but cops are simultaneously supposed to take the time to evaluate the threat to their safety.

I think you have misunderstood the order of operations in a violent encounter. The issue of chambering a round is in light of the fact that you have already identified an immediate violent threat and you need to end that threat. The entire question of carrying chambered/empty is completely separate from threat identification and whether or not a shooting is justified.

You also simply don't appear understand the time scale in which violent altercations and legitimate responses take place. They happen quickly, and so once a threat has been identified you need to remove as many barriers to action as possible. Adding 1/2 to 2 seconds can easily be the difference between life and death after you've already made the judgement about the situation. Again, the issue here isn't whether or not someone has identified a threat but rather how quickly and effectively they can respond after they've identified the threat.

If we want to speak intelligently about use of force and police reform we should avoid conflating unrelated issues (i.e. whether or not an office acted appropriately versus the ability to act properly after a threat has been identified).