Censorship only makes Martyrs out of idiots. At some point you've got to trust that the majority of people in your community are smart enough to ignore bigotry. I find it hard to believe that reading a racist comment could sway a reasonable human towards racism.
People need to see the injustice in the world before they can fight it. If a better community is what people want then the community should choose to fight that battle. I heard Alexis say in a talk once that 'if you treat people like adults, guess what, they treat you like an adult too'.
I may be offended or infuriated by the comments I see somewhere but I still want to see them, lest I convince myself that ugliness doesn't exist.