Nothing, and making it illegal won't save them from anything either
It's like with drugs. Banning them doesn't stop people from getting drugs, but at least from openly promoting and using them in public spaces.
Banning it lays the groundwork to imprison communist teachers.
Bans do a hell of a lot for those who aren't willing to risk the consequences of theft or manufacture and don't have any social connections beyond immediate family, even for targeted bans on a specific population of something which is incredibly prevalent such as alcohol can be incredibly effective to the point of denying a desperate man access to his vice for years or even decades. The only reason bans get a reputation of ineffectiveness is because of non-whites who will somehow find a way to access it regardless.
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