As a Non who has learned a bit about NPD, I wouldn't say that I or the general public treat those with NPD as non-humans, but I would definitely agree that we treat them with distrust. If I meet peers in a social situation I will interact with them in a genial way, telling stories from my past, making jokes. If I encounter a person in the same atmosphere who, for whatever reason, I know has NPD, or who is clearly displaying some of the major signs, then I won't interact with them in the same way as everyone else. I do not want to exchange stories from my past with someone with NPD because he or she very well might use that knowledge to hurt me later. I do not want to joke with someone with NPD because my words very well might end up twisted into something unrecognizable and thrown back at me or used behind my back.

So yes... self-protection, distrust, and honestly... fear. Most people I interact with on a daily basis work within the same general social rules as I do, but people with NPD do not. I am afraid of them because I cannot count on them to act within the normal social guidelines, and they very well might end up hurting me.

You mention clinicians, and I also think clinicians should be able to interact better with people with NPD. They are trained to handle those interactions. I am not.