What if you don't do it anonymously enough? And they trace it back to you? Not that this has ever happened (I have no idea. I'm assuming not). But being paranoid isn't unwarranted either.
If he does not report it, and somebody else does, then he runs the risk of being rightfully accused of hacking, as the motivation can be understood as financially motivated.
You're often opening up yourself to a LOT of bad exposure, where you'll be accused of hacking the software (along with the 20+ jail term this might eventually entail) and just generally putting the spotlight on yourself as a potentially dangerous person.
Better to report anonymously, or report directly to someone who might appreciate or is responsible (and hope they appreciate responsible disclosure).