alt Hacker NewsI'm not a lawyer. But it seems to be the same as accepting the terms of service of some product you use or clicking on a "Yes I'm 18+" button to gain access, isn't it? If you somehow suffer from a negative outcome, it puts the blame clearly on you, from a legal standpoint, if you lied about your age or ignored the TOS.
It says nobody is liable for the signal being wrong i.e. the parent is allowed to give the child an over 18 account or full access if they think that's appropriate.