Hopefully, students will be smart enough to realize that "The Wire" is a work of fiction (as you and others have pointed out). However, the difficult thing about teaching just from research and theory is that it is extremely difficult to gain a concrete understanding without a concrete presentation.
When I was going through the teacher education program in college, we read a lot of (what I thought were very compelling) scholarly articles explaining how current practices (regarding instruction, assessment, and so on) were flawed and then proposing better practices.
The discussions we had were often of the "Okay, I see what the author is saying" variety, but ended up with very little actionable follow-through. I remember getting in trouble for trying to heed the advice of the research ("I don't care what the research says, we're doing it this way and that's final.")
What I am trying to say is that research and statistics are all fine and dandy, but the students at Harvard are mostly white and mostly from reasonably affluent families who live near other reasonably affluent families. Ideally, we could study those realities directly via fieldwork, but that's simply not a possibility for most. So, in lieu of giving these students a completely abstract understanding without any lived experience (even if it is vicarious and fictional), "The Wire" comes in.