I think the information we have is a bit limited.
Firstly, I agree with the person who has pointed out that no way are they sailing the whole time they are there. I had this kind of upbringing (well not the private school, but the weekends sailing in Wales), and even though we were all keen sailors, the days when you can sail all day are quite limited due to weather, and the weekends we spent at the caravan therefore also involved a lot of time on beaches, walks, BBQs, bike rides, etc. and also meeting other kids who were down there a lot too.
So they 'don't really like' sailing (nobody has said they hate it BTW), but regardless of how this is being portrayed, they will be doing lots of other things down there too.
I agree that kids shouldn't have to spend all their time doing something they hate, but it's very unlikely that this is actually the case.
I also spent a lot of time looking around deadly dull ruins as a child, which was deadly dull, but that doesn't mean it was wrong of my parents to do it.
D