If we allow discussions advocating piracy, soon someone will get the idea that it's OK to send links to pirate sites via PM. Soon afterwards, they would start posting them publicly.
You could make it clear that the line is drawn there. Which means that you could ban anyone who purposely post a link to a warez site. I honestly do not think that there would be more warez links, just because people express their opinion regarding the issue. Just make it clear that whenever the line is passed, the user will be banned.
I do not understand why we should ban peacefull discussions at all.. But it is you who are the one who makes the rules, so i guess must abide them if i want to post here.