They said from the beginning that Disney+ would be family friendly and Hulu would be for the adult content. It's not a matter of parental controls but rather brand protection. Disney as a brand has always been associated with family friendly content. That's why more adult films have always been on another label (Touchstone, Hollywood Pictures, etc).
I don't think they'll lose that market because the pure nostalgia play is there. Maybe some, but not a majority. And Hulu will be expanding internationally soon.