I do NOT know California Law in that regard. However what I do know (unless you demonstrate to all the rest of us that the article misrepresented the ruling) is that FROM THIS POINT onward, you must have teacher credentials in order to teach at home, or operate as a private school, etc. Or likely if not yourself you’ll have to hire one. This is no doubt partly a job creations program. That is painfully obvious. Unions are sorta good at that and no question this legislation moves to that end. As to the family’s actions, that is largely irrelevent in this matter of punishing everyone else for someone’s alleged oversight.
This opinion doesn't outlaw homeschooling, but it can help provide cover for those who would want to deny a homeschooler being listed as "persons capable of teaching" and able to file as a private school to obtain exemption.