The Federal govt has no Constitutional authority to tell a school what to feed their children. The state is reserved that authority if it chooses to do so.
If the government can't stop abortion due to privacy then why can I not allow my wife to sell her body for cash? Why can I not smoke pot? Neither of those things are infringing upon anyone elses rights. It can be argued that abortion infringes on another humans right to live but thats not the point