1) What harassment?
2) What criminal acts?
Sensitive info scrubbed information dumps aren't illegal, and I am pretty sure he cannot prove the site is responsible for the hack based on the fact that the user who posted the link to the initial dump joined for the express purpose of doing so given the only messages are "hey his site got hacked" and "here's a link to a third party hosting service linking to a different third party hosting service."
And even if he can prove that the user that dumped it initially is the hacker and also had an account prior to the dump (obviously the dump account is a sock in this hypothetical), the lawsuit would be against that person, not the site.