I suppose you want him to have an English dialect map that includes Spanish speaking countries? It might ease your sensibilities, but it would be meaninglesss.
While it must be truly invigorating to get the rush of moral superiority you feel by pointing out perceived racism, it is absurd nit-picking that allows you to arrive at your conclusion.
Every other nation in the Western Hemisphere has a name that allows the citizens to be uniquely identified: Mexican, Canadian, Haitian, Brazillian, Ecuadoran, etc. Tell me, what do you propose we call citizens of the United States of America, other than "Americans"? I once was the only American working at an international school. One time, and one time only, a young Spanish man from Madrid made a stink when I referred to myself as "American." The 2 Argentinians, the 1 Brazillian, and 3 Englishmen in attendance all rolled their eyes and collectively told him off with the same question I just asked you. It's absurd, it's over sensitive, and it screams out "Pay attention to me! I'm pointing out oppression!!"
The author doesn't try to cover AAVE because the vast majority of the African American population outside of the South emigrated FROM the South less than 3 generations ago. There's an entire field of study on AAVE, and its not his field. FYI, I'm from the south, and to most northerners, AAVE and "white" southern dialects sound extremely similar, to the point where a white Seattle teenager I encoutnered saying "yall" picked it up from the hip hop culture he was immersed in. It's not necessarily that AAVE is derived from white southern, its that the two dialects grew around each other, with rather extensive interaction between poor whites and black slaves in the rural south. I would say the influence is surely two way, and know for a fact that many of the words my family uses are African in origin.