I've read something that appeared official on FR already addressing this complaint yesterday. There is no legal issue here.
Theoretically there is but not one worth pursuing. Even if Trump or the Quicken Arena had a deal with ASCA or whoever, political events are exempted. So technically Trump's campaign illegally used the song but the owners of the music, Michael Jackson's heirs, would be the ones to sue and not Harrison's heirs. And the damages from a one time use would be so minuscule that legal actions would be a waste of time. So Trump used it, Harrison's family acted all outraged, Trump won't use it again, and it's a dead issue.