I see no problem with the government determining what information can and can't be made available to children at public school. This isn't the government making certain information verboten universally, it's ensuring that other people cannot indoctrinate your children with information you find objectionable. Children's minds have become the new front-line of the culture war, and this is an entirely reasonable reaction.
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.