A friend of mine was at a bar in the LES and Bill Murray got behind the bar and started serving people. No matter what you ordered he'd just make you a gin and tonic.
Another friend of mine was at Bembe in Brooklyn a few years back and Bill Murray came in, skipped the line out front, and came out a few minutes later with two bottles of water and just walked away. My friend asked him if he really went in to just get water and he said "Yes. Your friends will never believe you."
Both are friends I completely trust to not be lying, but Bill Murray was right. I don't believe them.
He doesn't have to "perform for an audience" in parties and social scenarios -- tons of actors don't do any of those things.
(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.