"why would anyone under 60 remember LBJ?"
I've never understood the theory that only those who were alive at the time of an event can possibly know anything about it. Johnson being sworn in on Air Force One of the runway of Lovefield Airport in Dallas, with Kennedy's widow standing next to him in her blood-soaked clothing, is simply general knowledge. The photo is an icon of 20th century American history.
When was the Battle of Hastings?