I do wonder a little, if we are so against certain topics in the classroom not just because they might be seen as offensive to members of the classroom, but also because their semantics might be misconstrued in conversation which could lead to further confusion for or from the speaker rather than them being able to convey their meaning with ease (semantics and pragmatics). For example, talking about sex as an act (sexual intercourse) versus the sex of a person (or rather gender) could easily be confused and lead to a barrel of confusion for the speaker. Perhaps they should be avoided?
Overall however, I don’t believe this. I think as a language, any language be it English or otherwise, might be imagined as a tree. Those who are taught only the essentials, or ‘polite’ and ‘safe’ topics are only able to climb the bottom branches.