As someone with a similar background to your friend, you don't code switch for the people who already respect you, it's for those whose respect you want. I wouldn't speak in my low-class, rural dialect around prospective employers or customers or anyone else I might want to perceive me as competent. There may well be a racial component to how AAVE speakers are treated, but the class component is non-negligible.

EDIT: Judging by the downvotes, a lot of people disagree with my experience. I'd love to hear your experiences or rationale.