This is called a motte-and-bailey. We were discussing a group trying to ban books about the Holocaust, and the larger concept about groups of parents being able to ban anything by whining about it enough. You put forward a different argument you think is bullet proof about banning sexual content with the implication that this argument defends the much weaker argument about banning Holocaust books or whatever books the mob may choose.
Just pointing that out. It’s a common fallacy and one that feels right, it isn’t necessarily done intentionally.
The freakout about sexual content is fabricated and designed to play to emotions. School libraries already ban sexual content. There’s no smut or erotica at them. The small handful of books that people wanted to ban were either educational or were similar to many books that were not targeted by those parent groups and the sexual situations were not the focus of the book. The main similarity was that they were about LGBT sexualities.