So you do censor your site to some extent. Good. That at least gives your site a fighting chance against people using it's previously declared status (totally non-censored) as a freedom to post potentially extreme or at worst even peadophiliac pornography where children are present.
Everyone - and I mean everyone - draws the line somewhere. This subject is hugely complicated and there are no rights and wrongs, just differeng philosophies and differeing interpretations on those philosophies.
  Loz