Not against the rules, no.
Is your problem that it happened, or that you don't trust the person who did? Would you still expect action taken if it were someone you know and trust?
If allowed my fear is someone claiming it is for good "to stop hackers" and just collect accounts. I'm guessing a list is made of usernames and passwords. I guess I don't like the idea of someone being able to claim being a good guy when making a list of accounts and passwords.
I guess it's becuse it could be sold and we see lots of unused accounts, from people who claim they were good at first changing passwords. I guess I see them doing the same as the "bad guys".
Ohh well guess I'm over thinking it. But was nothing against OP.