It isn't porn cause this specific image doesn't have any sexual action action happening in it.
Calling this porn just cause Zelda look hot is like calling all classic paintings and sculptures porn just cause they have someone 90% naked.

Yes, her dress is see through, but that only makes it as lewd as a detailed drawing of a woman in a bikini. Which we have multiple entries for that.

And being part of a porn story is fine cause:
A) If you didn't tell me this was part of a porn story, I would just assume to be a random lewd image.
B) We have multiple entries where they take parts of porn and hentai and use that part for a joke. Or to just show how good the art style something is.

And lastly, a image doesn't need "anything more going for it".
A high quality lewd fan art image can just be a simply high quality lewd fan art image.
At this point that's a simply enough reason to be uploaded into KYM. Fan art to be enjoyed.