"TREK TALK ONLY" and "NO GENERAL COMMENTS ON MODERN SOCIETY".
Seriously, this quite a blurry line. When people are talking about something like racism (or some other topical subject) within context of the show it's inevitable to bring in real world examples and experiences as a comparative standard from which to assess the accuracy or calibre of what we're seeing onscreen. If you can't discuss comparative examples from the real world then the discussion of the subject at hand becomes essentially meaningless.
If the examples and ensuing discussion are "on point" in regards to the subject discussed from within the show then it's definitely relevant and cannot fairly be prohibited.