Grammar Nazis annoy the hell out of me in ordinary circumstances. Racist grammar Nazis? Even more!
I speak or read English, French, German, Russian, and Latin. I can usually puzzle out written Spanish, Italian, and Portuguese.
And you know what studying a bunch of languages ought to teach just about anyone? Language and grammar rules exist in a state of constant flux. Nothing about dialects is sacred. There is no right and wrong, there is only change.
Nothing about any American dialect says anything about the people speaking that dialect.
If we don’t like the West Virginia dialect or the Black English dialect, but we do value the high-prestige New England dialect, that says nothing about those dialects.
It says everything about our prejudices toward the people who speak them.