I was expelled from school for life when I was 15, leaving age then was 16. It made me realise what life really was like when I got out there and had to find a job. I ended up studying at night class a few years later and went on to do my diploma. Never looked back had a great career. It was my wild years and it was youth. He will do fine, I think the school will see their mistake within days. Support him as I know you will, but don't let them wiggle out of it. Contact local press.