So long as the appropriate royalties are paid, anybody is allowed to to use any licensed music.
Of course, the Pettys, if they even own the music, are welcome to pull the publishing rights from ASCAP, BMI, etc. Of course if they do that, the royalties that keep them from having to hold real jobs will dry up. But at least they'd be putting their money where their mouths are.
As Daily Mail article says they can be
stopped from running it in a campaign ad.
For a rally as long as they pay the music
license fee they can play what they want.
Maybe if Trump campaign puts up replays
of the rally they can mute the song IF
the music publisher objects to it. “Your
video contains content that belongs to
somebody else and has been muted”
Millions watched the rally last night, live.
A lot of people heard the song.