bapu
All legalities aside. If an artist makes a public statement that they don't want a candidate to use their music they've made it clear they don't support the candidate.
I suspect that's the goal of the artist. No court, no tom foolery, no $ sought. Just a simple statement to the world (that listens) that says "I do not support thee".
This has to be right. Trump can enjoy Queen 24/7...except for a few minutes at a campaign rally? Yeah, that's doing pretty much nothing except, as you say, making it clear the artist doesn't support the candidate.
Artists need to deal with the fact their fans are made up of people who would disgust them if they knew them, and those people are listening and being inspired by the artist's music all the live long day....
Resistance is futile...