I'll say again, its not about the character, its about how the image is rendered to appear. You can make any character look older or younger and if you choose to do it with nudity then its best to clearly make the final render appear over the age of 18.  We have a large team of mods/coords (52 not including admin) and we vote on the questionable images so there is no one or two persons that see it a certain way then take action.