Thanks for all your replies. I'm amused to see that this thread has gone the way of most AIBUs, and started arguing with itself!
I think I'm going to refuse XP, for the following reasons.
If this flight was something that DS was going to be doing with a trustworthy organisation, such as school, navy (we're v. close to a naval airbase) or air cadets I might think differently, but the fact that I don't know this pilot from Adam, and can't trust XP to risk assess in the same way that I would has a massive bearing on this.
XP has constantly done things with DS that I feel are a bit reckless. As one example, DS is a massively sporty, outdoors, daredevil kind of boy, and I love to encourage his interests in this in a safe way- after school dinghy sailing club, etc. He also likes surfing, so I enrolled him in the local surf lifesaving club, which is excellent (sadly he hasn't been able to do summer sessions on the beach yet, due to COVID). XP- not an experienced surfer- takes him surfing with a random friend of his- not usually a problem, but I learnt in retrospect that one terrible weekend this summer which combined sunshine with very strong winds and a massive tourist influx down here, and which resulted in innumerable coastguard shouts and at least one local drowning, they went to the beach and DS got into difficulties and had to be pulled out of the sea by an adult.
In other words, XP has got no fucking common sense. (and I'll just touch on the fact that he still assumed that he was picking the kids up from school and having them for the weekend whilst isolating with COVID symptoms and awaiting a test a couple of weeks ago. Just because I want to vent, really
.)
Also, probably the only reason I know about this is that it would involve pulling DS out of school on Wednesday. Whilst his school does allow this, it is the kind of privilege I invoke very, very rarely- and especially not right now, when they're only just starting to get back into some kind of routine.
Replying to a PP: I guess if I was to pick 3 no nos for DS, it would be potholing (luckily we're a long way away from pothole country, and the saga of the Thai boys may have put a generation of kids off potholing anyway!), light aircraft and motorbikes. Diving- well, we have a very good, trustworthy dive centre down here, so if he wanted to get into that (and fund it himself!) I'd be fine with that.