Hmmm. Maybe Beach Geezers would be more accurate now.
It wasn't age then, and it wasn't recent. Brian was trying to get out of his "I'm a psycho whack-job" mode and go back to touring. This was in 1979 in New Haven, CT. It may have been his first concert tour since refusing to board the plane to London, when an apple-faced Oakie named Glen Campbell was called to take his place (later filled by Mike Johnston).
I've seen the Beach Boys in Houston, Atlanta (thrice), Austin, Boston, and San Diego since then, but never saw Brian on stage again. I've even seen the late Jan Berry on stage with Dean Torrence twice since I saw Brian Wilson.
Recently read the biography Catch a Wave, though, gave me a completely different insight into the boy and man.