I just wanted to add to your comment that he might not be "willingly" going home. His abductor is going to jail. This kid doesn't really have anywhere to stay other than with his parents. Depending on his current age and what the Missouri laws are, he is probably not legally able to be emancipated. He's probably legally bound to his parents.
I think we're all assuming this guy just up and took this kid. Why does it have to be any different than these sexual internet encounters where the people mutually want to meet after conversing on the internet? Maybe this kids child life was less than desireable to him (kids are rebellious) and maybe this guy promised him constant video games, lax rules, not an alcoholic like parents, etc. That might have seemed really attractive at the time and the kid arranged the pickup.
I'm going to coin a new phrase with this
Statutory kidnapping.
Probably the smartest thing said...well idea of what really happened. It could be wrong, but when you think about it...it does sound logical...