No, it's not. It's just erroneous here; AAVE has an internally consistent grammar just as any other language does. I know quite a few people who code-shift between AAVE and standard American English, just as I do between that and the (admittedly somewhat less different) dialect of my youth.
The remainder of Overtonwindow's comment flows from that error and one other, which is to assume that AAVE is a "degraded" form of standard American English. It is not; it has old and many-branched roots of its own, only some of which lie within American English.
But who knows? Perhaps Overtonwindow is a more accomplished historical linguist than those on whose statements I here rely.
Yes, clearly. I just meant "… in a vacuum" or "… with the implicit understanding there is some _true_ grammar". In one sense, yes, utterances/productions can be grammatically incorrect with regard to a particular grammar under discussion, but if those utterances/productions can be said to be a part of that grammar, eventually the grammar needs to change to accurately describe the state of the world.
(Ultimately I have to think some of this comes down to "misperformance" where the speaker _knows_ their production is invalid. If enough speakers "misperform" but begin to hold the idea that these speech acts are not actually invalid, is that what tips the scales in favor of changing a grammar?)
The remainder of Overtonwindow's comment flows from that error and one other, which is to assume that AAVE is a "degraded" form of standard American English. It is not; it has old and many-branched roots of its own, only some of which lie within American English.
But who knows? Perhaps Overtonwindow is a more accomplished historical linguist than those on whose statements I here rely.