Anyone, even cops, can do good things
It seems to really befuddle the copsuckers, even though it seems very simple to me. That cops are bad, but can sometimes do good, and that people who don't buy into the cult's propaganda can recognize the good acts as good without falling for the cult.
If a cop shoots a guy who is making a credible threat to kill an innocent person, he did a good thing. Just like if (or when) a shoe shine boy shoots an attacker he has done a good thing. Or, the same goes for a serial rapist shooting another bad guy who is in the process of archating, saving an innocent in the process. Or, if one of these examples protects private property from violation. A good act is a good act regardless of who does it or why.
You can be UltraHitler and still, in one situation, do the right thing. Your past and your future have no bearing on what you do in that moment. And I would be grateful to you for doing the right thing.
But, that one moment doesn't excuse all the other bad you have done and will probably continue to do. No, it really doesn't.
Yes, cops can save lives. So can pet store employees, mafioso, bank robbers, grocery store cashiers, and any other person on the planet.
The only advantages cops have in the area of responding to trouble are that they are exempt from the "laws" against gun possession that they help impose on the rest of us, so they are generally prepared- toolwise- to deal with (other) bad guys without worrying that simply showing up with a gun will get them in trouble, and they have a communication network which alerts them to trouble spots. (And that advantage is going away.) Even so, they still manage to avoid doing anything helpful much of the time, and quite often make things much worse than if they had stayed away. Frequently even attacking the innocent when they can't figure out what's going on. Or, if they are just having a bad day and a confused, scared person who has just been violated doesn't comply to absurd orders and demands fast enough.
Cops only appear "necessary" because most others have been legally required to be useless in situations of trouble, and cops are zealous about maintaining this special status for themselves. Stop accepting this situation.
But, just because a person is a cop doesn't mean they can never be good or helpful. Sometimes they are. But when they are, it's not their status as a cop that is to be praised- it is the actions of an individual doing the right thing in spite of being a cop that should be praised. And their helpful action doesn't apply to the cops who weren't there and didn't do the right thing.