Chrissy Hynde’s parents are HUGE Rush Limbaugh fans. Rush pays Chrissy half a million a year to use that music for his program. The fact that the words to “My City Was Gone” are never used protects Rush from copyright violations.
If there is no copyright violation Rush would not have to pay anything. Knowing his mercenary tendencies, I doubt that he's paying out of the kindness of his heart. That being said, one doesn't avoid copyright violations by not mentioning the title of the song.