A distinction has to be made between the different kind of violations.
Crossposting is a minor violation and such topics will be closed.
Some threads of which a mod/admin is not sure whether it is illegal can be moved to a hidden forum for a second opinion. But threads that are blatant violations, such as crack requests or help on illegally downloaded stuff will be deleted as soon as I spot them (other mods/admins may have a different policy on this).
By leaving an illegal thread on our forum, the topic starter might still get what he (or she) was after. Secondly, by leaving those threads on our forum, search engines may pick up on certain words and people would only come to this forum for the wrong reasons.
And finally, by removing the threads we prevent all discussion on these matters. We are a legit forum and as far as I am concerned there is a zero tolerance for blatant violations and in this I am probably stricter than others....but that is what I am here for