Ok, so what's the cutoff for "those areas"? See that's where it gets fun.
My neighborhood is pretty mixed, but I'd guess mostly white if I had to think about it. But "white"--some of those folks might have some dark in them, if you know what I mean Some of them (like my own kids) are obvious mixes of two ethnicities, but one kid WAY more than another! So logistically, how can it be done? What are the cutoffs for both "whiteness" of a neighborhood, and "whiteness" of ethnicity for each resident as determined by some measure?
I'd hate to think I couldn't call the cops because we had too much "off color" happening on the block! Maybe some burning crosses can convince the Joneses down the street to sell, once they go we'll be under the threshold.
Then, let's say you work all that out--will there be rules to prevent dilution of the pure areas where police will still be?
Bottom line -- cops are hired to do their jobs. They are paid. They have nominal rules of conduct. If they break those rules they should be held accountable. Just like if I harassed someone at my job or in the public for that matter, no matter what the reason, I'm going to pay the price for it. If I felt that was too difficult, there are other lines of work for me. And "harassed" is a pretty tame description if it comes to the worst of them, those that kill people for no damn good reason.
Edit: and I actually do agree with the mental health filtering. What are the chances the police associations are going to go along with that, assuming it's something serious and done right? I'd say somewhere right around 0%. That said--if it's anything like those personality tests (myers briggs etc) that some workplaces do, you can fool those easily if you care to. I cared to, and did just that when we did those in our dept just to troll my boss I picked a different persona and answered appropriately. I'd hope a mental health test would not be something you could trick.