As long as the fees/royalties were paid, Heart has no say. They cannot tell one person who pays the fee 'yes' and another, who pays the same fee, 'no'. It IS their intellectual property but, since it's published, it's for sale to whomever wants to purchase it. Too bad, so sad, nice try.
I guarantee, nobody at the RNC last night gave a dern whether Heart, the 'has been's', are J-Mac supporters or not. The song fit and it added to the festive moment.