I know free speech is something a lot of people here hold dearly, but it can be bad for dialogue. It might be cute to even argue in favor of disgusting things like being pro serial killer in a debate. However we need to focus on how certain beliefs can harm society and how we should not even tolerate those beliefs. I would propose banning certain topics such as what follows.
1. Nuclear war is good
2. Murder is good
3. Rape is good
4. Women are inferior to men
5. Some races are superior to others
These topics can have real world consequences, particularly since the site has a very young demographics and are very impressionable.
I know this might be controversial, but the site should eliminate any notion that all speech is acceptable or will be tolerated. Anything considered disgusting by normative ethics should be banned.