Revealing a heinous crime like rape should be grounds for the hacker to have immunity from prosecution. Same if they revealed a murder or major theft. Otherwise hackers have an incentive to just pretend they didn't see the information. Of course if while hacking they committed any sort of breach that was serious enough then immunity should not be granted but otherwise grant them immunity.
I do not fully understand why hackers would expose rapists. If someone is labeled a rapists, then they have already or are, serving a sentence. Secondly, rapists are listed on a registry which is easily accessible to anyone on the Internet. Hackers on the other hand our a whole different criminal and I don't see why or how they would expose rapists. They should, of course, face fines and jail time for whatever systems they are breeching.