NSFW images on Wikimedia tends to be a very hot button issue when it comes to Wikimedia politics. There obviously some cases where such images are needed, and there is a lot of debate on where the line should be drawn (or if it should be drawn at all). Wikipedia is traditionally very anti-censorship in any form. Fun fact - Wikipedia founder Jimmy Wales lost a bunch of his user rights when he went on a deletion spree of classical art work containing nudity.
There is an automated filter for child sexual abuse images. Its not public what the procedures related to it is, but i assume if it goes off the fbi gets called.
No means or methods are necessary. I am familiar with the work of the NW3C and other groups who do important work in that area. My sympathies to the janitors. Truly difficult and important work.
