I understand the intent even if I don't agree with it entirely, but what is the school to do when a 300-page book has one page of explicit content? Does that taint the whole book and now a teacher has to scramble for an alternative assignment?
How about classes--that all of us who have grown up in the public school system have taken--that specifically educate students about physical health and sexuality. Was Sex Ed really that bad? Can every parent be made to sign an affidavit under oath that they either 1) firmly educate their children in every facet of sexuality or 2) ensure that their children have absolutely no access to explicit content outside of school?
Why are we trying so hard to hide children and young adults from the world that exists around them? I assure every parent that their kids have already seen and heard everything that they might read in a school book or learn from a teacher. Isn't it better to have them educated on it than ignorant to it? Do you really expect kids to bring such topics up to their parents to learn more...especially when they see you fighting so hard to keep it from them?