We could say that the main argument expressed in this text, is that Black English can't be thought of as a mere dialect under the veil of White American English focusing on its differences.
Anything less than recognizing Black English as its own separate language, would be an injustice and an oversight. Language is an integral part of culture and identity, it functions as one of the main tools for self-expression and assimilation of tradition. Taking Black English only as a dialet would represent a complete dismissal of the distinct history of African American population and their journey. Since slavery to modern times, black culture has come a long way towards embracing their uniqueness as a form of empowerment, and language has most definitely been a crucial tool in achieving this goal.
Hope this helps!