What is it Scott should have said that would have carried anything like the same meaning? "I have a roommate who fits the stereotypical image of monolithic black culture held by the Atlas Anti-Racism League"?
Alternatively, something like "inner city black kid from Charleston". You can refer to someone as dark-skinned and from a less-than-ideal neighborhood (although who knows if he is) without calling him "gangsta-type" and saying he's from "some hood".
So "gangsta" and "inner city black" mean the same thing to you?
No, of course not. "Gangsta...from the hood" implies things (mostly, er, about himself) that I don't think Scott meant to imply. Racial insensitivity is in the form, not the meaning. As Gustaf said:
Your attempt at providing an example what Scott could have said that would be racially sensitive eviscerates not just the form but also the meaning of his post. The fact that his roommate is black does not in itself explain why he and Scott would be "polar opposites." If Scott is not supposed to use terms associated with a certain subculture, what terms should he use to indicate that subculture?