Apparently there were a couple things behind it. Costello wanted to play Radio Radio, but his record company wanted to push Less Than Zero as the first single from the album he was promoting. But Less Than Zero was pretty specifically about an English fascist politician that Americans wouldn’t be familiar with or concerned about, so Costello didn’t see the point. Supposedly the sponsors and network were uncomfortable with a song that was so openly critical of mass media in general and commercial radio in specific. So Costello initially agreed to play Less Then Zero as his label dictated. He clearly changed his mind. Pissing off his label and the network significantly. Michaels on the other hand is a noted control freak with a habit of banning people from the show. He likely banned Costello just for pissing him off. He hadn’t done as he agreed and threw the timing of the show off completely. I’m sure all the pissed off executives didn’t help matters.
Least ways that’s how I heard it.
