And I had a thought (quelle idée!) - Maybe the guy lost re-election and the song was rewritten. In a related story, when I first learned Charlie on the MTA as a wee lassie way back, uh, well anyway, the final verse went Fight the fare increase! Vote for George O'Brien, get poor Charlie off the MTA! Years later I actually went to MTA country, where it was the MBTA by then, and they were singing it just Fight the fare increase (bis), and there was an O'Brien highway which I assumed was named for George...

Out of favor, out of song, I guess... is it possible that Charlie/MTA was written originally as a political shaggy-dog story?