He was driving himself to work on a country lane, clipped a curb on a corner that pushed him off line enough to clip a tree right by the side of the road. Span the car round and put it on its side.
There’s a lot to unpick here…
But now I’m wondering if that was really the right advice
Yes. The police were involved. There will be a record. If he didn’t let his insurance company know then this would probably come back to bite him in the future.
Has he now effectively made himself uninsurable?
No although the costs will go up.
Glad your son is OK, that is the main thing here. Most of us have had accidents in our driving careers, learn from it and move on.