car insurance company wants reimbursed for non-insurred accident

His status as a minor is only relevent while he's still a minor. Now that he's an adult, he can be served with a lawsuit or enter into an agreement to pay what he owes the person he hit. That $25,000 amount is likely inflated over the amount the company truly thinks the claim is worth. I suggest that this young man contact the insurer and attempt to negotiate a much lower settlement. And he should not agree to anything until he's seen what evidence the insurer has against him.

If he lived the majority of the time with parents or gaurdians at the time of the collision, he may be covered under a parent's policy under the family car doctrine.

Ultimately, he would be well served by finding an attorney that defends tort claims for private individuals. It may cost him some in fees to the attorney, but I imagine the savings would outweigh the costs.