Legal rights of composers

Helen asks a question about the posting of her own performances and the copyright of the composer. Tim Rutherford-Johnson says that composers have the legal right to stop uses of their work that is misrepresentative, what he calls "moral rights." I know nothing about British copyright law, and not enough about U.S. copyright law. So I can't comment on either of these posts. But I can offer a related question of my own. Augusta Read Thomas is coming to DePauw for our Music of the 21st Century festival. I offered to perform Gusty's Sonata for unaccompanied trumpet (1986), since I like the piece and I've played it before. But I have been informed she withdrew this piece in 2001, along with many of her other early works. My question is, what are the legal ramifications of withdrawing a piece? Can a composer bar any performances of a work, even if the performer has legally purchased the piece? I certainly can understand respecting the wishes of a featured composer for a festival, but I would like to play the piece for a faculty recital.