"Actually, it's a legitimate concern. The overwhelming majority of home-schoolers are motivated by a desire to ensure their childrens' well-being. But there are a few parents who do use homeschooling to cover abuse."
Yes, there are some people who do evil things. And there are already laws to cover those evil things. AFAIK, it's illegal to abuse children in every state in the union.
Unless you send the children to public school, I can't see how the abuse this judge is concerned about could be addressed. Sounds like he just doesn't think anyone should be home-schooled.
What about abuse of the little ones? Maybe all should go to some sort of government daycare a week after birth. Moms staying home with the children until 1st grade could be dangerous too.