Wikipedia is censored (just ask the 2500 rc patrolers on any given hour).
There was lengthy debate about another picture, a naked girl on bike used in
the article nudism and managed to hold on despite several deletions. My own
point of view is that nude pix of kids is best left for your mother to show
to prospective suitors.
Album covers are designed to stand out - what next a war on Nirvana (album)?
Kid porn won't happen on Wikipedia, innocuous images may well be added and
probably get removed within minutes. Even adult porn rarely finds a place
on Wikipedia, see the talk page of Oral sex.
Filters probably have a place and it was someting I have discussed with
editors on-wiki, say during the Depictions of Mohammed petition. Many of
those pictures are illegal in some countries and could lead to a criminal
conviction.
Wikipedia invariably vets itself based on the overiding principal what is
good for the community.