If parents harbor a missing teen for a week, are they being stupid, or should they be allowed to do so?

A 15 year old boy disappeared after school. No sign of him. Police were called and searched day and night for an entire WEEK. He was finally found at a friend's house (the parents let him stay there and didn't contact his parents or police, knew he didn't even go to school)... If you watch the news you can see kids get abducted and murdered all the time, and the police were searching for this kid. So it stupid of the parents to not contact anyone...or was it entirely the kids fault? I mean, the kid is definitely to blame, but would you also blame the parents?