"No explicit content. Content such as nudity, racism etc. are not allowed in any of the group's works or in any comments. They will be denied/deleted. If you continue, you may be reported or kicked out."
You should separate "nudity" and "racism" one is ART and other is SHIT they are definitly not the same, and you can't report people for nudity because there is a nudity filter on deviantART (and an artistique nude section btw...).
But you can refuse nudity on your group, but do not affiliate it to racism