Von Bontee said
That's pretty strange, the way the Examiner's framing it as her "defiant response" to a Paul McCartney song when she didn't even write it, and Paul seems pretty incidental to song anyways. Trying to create a more interesting headline that "Liv Warfield Performs Song Which Mentions Paul McCartney", I guess.
Your comment made me do some digging, and I found a YouTube upload of the Letterman performance that mentions that Ryan Waters plays guitar. Maybe he wrote it for Warfield?
At any rate, I think defiant is an apt description, given the first line. Paul himself is incidental ...