Maybe. I give kids more credit than most people on here, i guess. All it takes is one moment for the kids to see the password, guess the password, or whatever. if there's a physical key involved, parents sleep.
A determined kid will find a weakness in the pursuit of freedom.
also nintendo's OS lets users add users to their heart's content. At least i haven't found a way to stop a toddler from adding 6 avatars....