Do you happen to be a parent? (And were you a kid? I suspect you must have sprouted from a pod.)
Nothing personal, but I fear for the future of kids raised on such a short leash.
This is a terrible suggestion unless the child in question has already shown demonstrably (criminally) poor judgement online. Such measures are likely to either instill the new member of the family with an intense distrust and rebellion against the parents' authoritarian measures, or, if accepted, prevent the kid from developing a sense of personal responsibility.
I have never posted before, but felt compelled to create an account and respond to short-sightedness or naïveté of the parent poster (no pun intended).