Like I said, white people can't say it. That's the main thing. After that it's not as black and white. There are all kinds of influences after that, like culture, which you highlighted, etc.
I'm fine with that if that's how black people want to deal with the word. They can gate keep the word from here on out as far as I care. They aren't a monolith and I'm sure there's disagreement amongst themselves about how the word should be treated by themselves and by other people.
I don't need a perfectly consistent written out rule book. Other than I don't get a pass, which, like I said, I'm fine with.