I think that the censorship of viciousness rather than content is a reasonable compromise. I have engaged in a wide range of political and ethical debates on hn, and the few times the mods have shown interest has only been if I am beefing too hard with someone. The exercise of power is not to be superior, but to give the forum a sense of shape so that people can relate to it more readily. I think given the scale of the site they are doing good work.