https://www.wired.com/story/parental-advisory-chatbots-children-sex-and-alcohol/
I don't think "it might theoretically have this conversation" is a good reason.
That said, it's annoying to pretend that we can make these services "child friendly" like that (without making it far worse for others, and yet, still failing at this aim). An advisory or rating that it might contain mature content would probably be a better way to go.