That's fine until librarians or teachers consistently get it wrong. A school librarian's discretionary power isn't intrinsic, it is granted conditional on its proper use. I'm sure there are many topics that if a teacher or librarian presented to your children you would move to remove their discretionary power. The debate is merely on what topics cross that line.
> I'm sure there are many topics that if a teacher or librarian presented to your children you would move to remove their discretionary power
I would first consult with them, and, if necessary, go to the school board if I thought they were being unnecessarily intransigent (or too ideological). In other words, I much prefer working from the bottom up, i.e. from the local community level, rather than having prescriptions imposed from the top down.