That's a good point. I had forgotten about that scene. Again, I think that illustrates one of the main themes I got from this movie.... that adults don't really have it "all together" all that much more than the young'uns. (Love that word. LOL!) Honestly, life is often about learning to make the best of what you have. All the same, that doesn't mean you don't ever strive for better.... strive to do the best you can. Much as Owen imparts to Duncan in this exchange. It is GREAT to learn to be happy with what you've got, but there is also a time and a place to realize when you maybe SHOULD strive for more.
I think this exchange proves Owen realizes that, even if he may not necessarily act on it himself. The last thing I think he'd want for Duncan is to wind up spending the rest of his life just working at a water park, hence this exchange. By the same token, Duncan's mother's adventure/revelation parallels that in many ways. She's settling for Trent because she wants to be happy with somebody, and because it is hard having to start all over. Hell, having been married and divorced, she already knows that. So, she's inclined to ignore or even be unintentionally oblivious to how much of an @$$hat Trent is until he actually crosses a line (by cheating on her).
She, too, was settling. Maybe she didn't realize it, maybe subconsciously she did, but she was settling for Trent because it seemed like being with an @$$ was at least better than being with nobody/starting over again. But, both mother and son have grown from their experiences in this movie, and I think there may be brighter times in the future for both.