"Why not a little 'preaching' to Joran's parents?"
Same preaching goes for Joran's parents. Absolutely.
But I think an 18-year-old under my roof will always be a child to me. Not until and unless she's under her own roof and married. And by "child" I mean that he/she must abide by my rules. I think it's called tough love.
I imagine that if you ever have 18-year-old offspring (I refrain from the term "children" since it implies minors), they will do a lot of sneaking around if still under your roof. Either that, or they will leave the over-protection of your roof the first chance they get. It's hard to make an adult comply with certain rules. This, of course, doesn't mean that a parent has to finance their adult offspring's adventures.