He failed to choose the correct decision, so he decided to hide it instead of reporting his friend to the hightstaff, yes that was a wrong decision, but in my opinion, he is 14-15 years old, and I think its his first time to be in a situation like this, so he was confused and decided to hide it and keeping it as a secret, even if it was one of his family he must not hide things like those, yes I agree, but I am pretty sure if he will be in a situation like this once again, he will choose the right decision.
For me I say give him an other chance.