Just like killing is killing. Doesn't matter if there is a good justification for the action afterward. When you kill a person, that person is dead.
Fact remains fact.
Under this circumstance, although the victim did kill, he or she wouldn't have done it if the rapist hadn't attempted the rape in the first place. Pirating other people's hard work, on the other hand, is just shameless. The record companies may be charging too much for CDs and other music mediums. If no one buys, the demand goes down. Respect the law and respect yourself.