Eliezer: "In the original case, I talked about wiggins. Here, summarizing, I have to pick a better-known example of how arbitrarily excluding something is not only bad, but a case of trying to get away with something without justifying it."
At the risk (certainty?) of sounding churlish, ad Hitlerum is not a convenient shorthand. It's a logical fallacy which you've used a couple of times here. Being on guard against such thought patterns is the point of this blog.
Suppose that I referred to the non-human status of a 20 week foetus as an example of how "arbitrarily excluding something is not only bad, but a case of trying to get away with something without justifying it".
This isn't the space to air our political views.
Incidentally, I am pro-death and well aware that negroes are human (although I don't need quotation marks around the word "negro", except where required by grammar).
As I said, sorry to sound churlish.
You say: "The act of defining a word to refer to all humans, except black people, seems kind of suspicious"
This is gratuitously emotive and doesn't help to clarify your point.
Are you hoping to impress with your egalitarian conscience? Or are you hoping to politically bully your readers into agreement?
Please allow your arguments to rest on their own merits.