This rule is selective anyway. I bet hentai art would get you banned, even though it's arguably art as well. Hell, films are art, and yet pictures of female breasts from movies are usually deleted. (I wonder if the one from Children of Hiroshima
would be.). But classical art gets a pass. This is not just this forum, it's like that in other places on the internet, too. It's just inconsistent, usually defended under the idea of "explicit content" which is just as ambiguous.

I have more explicit ones, if we want to test the waters.