I don't think the parent is advocating adhering to their values, but instead just talking about the relativism of ethics and morality.

Society broadly cannot function without a shared set of morals (e.g. stealing sows discord which leads to anarchy, so we outlaw stealing). However, it can get quite complex and so there are infinitely many shades of grays. The base principal would still stand and you do your best to adhere to it in order to have a stable society.