Art Garfunkel is still upset about something Paul Simon did forty or fifty years ago. This should not normally be news, nor should it be a shock to anyone that he believes that Paul Simon is a terrible human being. He has an ax that needs grinding, and, brother, Art is not going to let it go.
I've been telling people that the real Paul Simon walks around with a suitcase full of money, a bottle of rye whiskey, and a street sweeper shotgun stuffed down his pants. There are skulls on his dashboard. He drives around in an old Cadillac he stole from Lead Belly. He eats veal and screams at waiters. He adopts rescue kittens and then gives them to people who de-claw their cats. He dated, loved, and then was mean to Taylor Swift once. He plays music for cash money on the barrel head. He rolls into town, slips into arcades and flophouses, and leaves with more cash than he arrived with. He has fathered 11,000 children. He has beaten up everyone in every band there ever was and he made Sting cry. He's the greatest monster in all of human history and you can call him Al if you want, but he'll shoot you down and impregnate your womenfolk.
He's the Conan the Barbarian of the soft rock crowd, and when he comes to your town, prepare for many, many lamentations.