(Ironically, that's a common advice people give to parents regarding their kids).
Besides do you know what's REAL melancholy for an "older, divorced dad"?
NOT partying at all, and not having people to love/care for them. Second worse, would be only having boring older people conversations and pass-times. If they can be that relevant that even 20th year olds are OK to hang around with them, more power to them.
What would be indeed be lame would be to TRY/WANT to party with younger people, and them rejecting you. Or partying with younger people but not being able to connect with another person out of "party" scenarios. Which I'd guess is not the case here.
Well, in that case he should still let him live his life.
But besides that, it's not just "fame" that does it. If the person is interesting, that can be enough.
He doesn't have to "perform for an audience" in parties and social scenarios -- tons of actors don't do any of those things.