Also, it would help if you or his father talked with him (not
in a disciplinary way) about
what happened. See
what his own thoughts were/are about the incident. Did he think of the possibility that someone might approach him while he was on the porch unclothed? If so, how did it happen that he decided to take that 'risk'? Or, perhaps he never thought of the possibility. His though process during this is important in trying to understand it.