The more I read about Mr. Parker, the less I support what he is doing.
It's obvious to even the most casual observer that Mr. Parker's child is in a hostile environment. Your primary responsibility as a parent is to raise and protect your child. It is not to engage in political grandstanding, nor is it to use your child as a sacrificial lamb. The child has no choice in this matter. This isn't an adult that's being forced to stand his ground, it's a child of 6 or 7 years.
This government school is beyond repair.
I just went and read about the whole debacle on Mr. Parker's website and IMHO he should not be allowing his son to remain in that school. It is harming the child to not be able to have his parent attend school functions. There is also some question in my mind as to how the teachers would "opt-out" their child if discussions arose "spontaneously" without causing harm to their child by having him singled out among his peers.
While I support Parker's right to not have his son exposed to things that are against their beliefs forcing the public school system to uphold those beliefs is wrong, and IMHO he is abdicating his parental duties to the school district and teachers which is exactly what should NOT be done.
He is, in essence, wanting to force public school officials to behave as a parental unit. I don't know how one would resolve this issue besides pulling the child out and either placing him in a private school, or homeschooling...