Appropriate Language Varieties for Particular Contexts?

Often, in pedagogical materials, you come across the (normative) argument that students who speak minority language varieties must be taught to code-switch and use official language varieties (i.e. Standard English) whenever “appropriate” (i.e. in official contexts like schools, jobs, writing…).  This  link is to an interview with an author/academic named George Yancy.  In this interview, he addresses some of the other messages/functions inherent in arguments about the “suitablity” of one language variety over another (around the 15 minute mark).  It’s an interesting listen.