There is no way a child would understand the full ramifications of their decision to be baptised. Hell most adult JWs don't fully grasp the concepts of what it actually means to be a baptised dub.
I have witnessed four bible studies (not mine) get love bombed and fast tracked through to baptism only to be DFed or DA within a year or so of their baptism, that's how well they "understood" this religion they were saying yes to.