I'd think you could show him some objective info (maybe from the AutoInt website) about how much clear is safe to take off and how aggressive you have to get for that to happen. Unless there's something wrong with him you should be able to educate him about the sensible use of abrasives. But maybe his dad's a bigger factor than we might think; some people you just can't talk to and when it's a father/son situation there can be bigger issues at stake.
IF he just isn't open to learning about this stuff, I don't think that means the situation is hopeless. After all, cars with thin, original paint that can't be corrected any more can still be made to look OK (gee, ask me how I know

) so a vehicle with minor marring should do OK with something like a glaze/LSP combo. Even something as simple as a Meguiar's "pure polish" topped with NXT oughta make for a big improvement.
I know somebody whose car *really* needs corrected in a huge way, but his frequent applications of NXT keep it looking, uhm....well, decent. *HE* thinks it looks a lot better than "decent" and hey, it's his car so why should he care what *I* think

I've seen how it looks unwaxed and I *will* say that putting the NXT on it helps a lot- it's a simple solution that works for him. Blowing somebody off just because they say "no abrasives" seems a bit extreme to me, nothing wrong with just making things a bit better.
Let's see...a pure polish topped with NXT topped with Collinite. That'd make it look a lot better and then there's claying and paint cleaners, lots of stuff that would be beneficial. Why not help a buddy out
