It’s not a gray area at all. Public schools are a public service paid for by tax dollars. The government excluding certain things from the curriculum doesn’t implicate freedom of speech any more than it excluding certain bus routes implicates freedom of movement.

Forced curriculum on students, at all, is no different than re-education camps; state sponsored indoctrination that both political parties (currently) support.

All education should be consensual

You're essentially saying school vouchers, and then the government doesn't choose the curriculum at private schools.

In a public school there isn't anyone else there to choose the curriculum. Everyone there is a government employee.

No, I'm arguing that forced schooling in general is an unethical act, on par with communist indoctrination, and there should be no government run schools at all