Children and Rights - Murray N. Rothbard - Mises Daily
There you have it, a libertarian addressing precisely this issue.
I've read that before. It's a retarded response. Negligent parents can threaten their children's lives, and those children can run away for their lives. Then, negligent parents can say their children ran away.
Likewise, it doesn't deal with situations of hostage taking when parents inhibit their children from leaving.
Basically, parents get off the hook from having to prepare their children.
That you disagree with the response is different from their not being a response.
Actually, it does deal with situations of hostage taking, since it clearly says that children must have the right to run away.
Hostage taking doesn't have to be a physical restriction. It can be a mental restriction where children are unaware of their rights.
The problem is Rothbard doesn't explain when or how children become informed of their rights.