Please do not use galleries from nhentai as sources. They usually have resized pages and are in lower quality. Also, the source field requires you to send a full link to the exact gallery, not just the general site you got it from. In this case I checked for the gallery on exhentai and they have about the same filesize, so this should still be okay to approve, but don't upload doujins you got from nhentai in the future.
The MILF tag being valid or not has absolutely nothing to do with whether a woman has children, but their body type / age.