This is not the kind of nudity that requires an NSFW warning, here's the definition of what does, from FAQ: "Nudity
: This flag is appropriate if your work contains explicit nudity; revealing
of a model or fictional character or revealing a full female breast including nipples
. " This drawing is an example of SFW nudity as it features no female nipple and no genitals, (nor an erotic pose to qualify it for sexual themes). You'll have to work out a more balanced perception of those things^^ no clothes does NOT equal NSFW/mature content.
Besides, on a sidenote, the staff is NOT doing their moderative job properly, they refuse to flag or delete deserving submissions if they belong to their friends or most popular artists (most infamous example: Raupture - for Alex
it is porn according to DA's definitions but the staff just refuses to admit that and to delete it for being porn it is, blocking the report possibility) , while they delete rule-abiding works and leave disputes of that expire(which causes the unfairly deleted submissions to vanish from the database and render them unrestorable) - they are extremelly unfair when they have a whim to.