If Little Johnny lives with mommy, wouldn't he be excluded from her policy unless she declared him as a driver?(which she couldn't do because he has no license) I doubt that he'd be insured under her policy at all without a license.
I have zero sympathy for mommy. Her "the car hydroplaned" bs-is indicative of her enabling him. I hope she pays a hefty tow bill, impound, and repair. Letting junior drive is dangerous.