"As for Dylan, I wouldn't be surprised if he has refused permission for his songs to be used on the show."

FYI, Mr Dylan could refuse permission all he wants, but he has NO legal control over who plays any of his already-released songs. Writers can control who plays their unpublished material, but once it's released for sale to the public on a record, tape or CD, anyone has the right to play, sing or record the song. They have to pay for that right, but on released material, the writer has no say.