Fair is fair. Your login BG is smut. The one you pointed out wasn't as smut as the one you released. There's no point in complaining, learn to release things that are 13+ but under 18, that means absolutely nothing inappropriate showing. As long as it's covered, we're with that. Your log-in BG had showed a little of the breast.
Keep your stuff under 18, or don't even release log-in backgrounds like that.