No one is prohibiting parents from sending their kids to parochial or private school. But what we’re talking about is essentially kids learning biological facts. Homosexuality exists. Sex exists. Pregnancy can be prevented. Some have lingams, others yonis.
These aren’t value judgments. They’re part of scientific fact. Why is it OK for parents to use the excuse of superstition to keep their children from learning these facts? Should it also be OK for believers in a flat Earth to forbid the school from teaching their children about the structure of the solar-system?