Pictures must be tagged for easier access, yes. And when a picture has a questionable content on it that's not marked by the artist/publisher and can't be defied with ease applying TWYS makes sense because it's better to add some tags, even if they're incorrect, than leaving no tags at all.
But TWYS is absolutely wrong approach when the picture content clearly stated by the artist/publisher. Why do you value your own opinion over the opinion of the person who created/commissioned the art? You have no ownership of it, you have no right to decide what gender and species the character is if it's clearly stated by the artist/commissioner. And continuing to insist on applying TWYS rule even after the artist/publisher stated it's wrong is just the rudest and most disrespectful action one could make. Because it's a direct neglect of the owner's rights. You don't own the character, you don't own the picture, and you have no rights to decide what tags should be if the rightful owner of the character/picture clearly stated their opinion on this matter.
Can you imagine approaching J. Rowling and telling her "I do not believe Harry Potter is a human. He's a fish because I saw him having gills and swimming in water. And your words about him being a human is a lie."
Doesn't it sound silly? But this is exactly what you do by sticking to the TWYS rule.
Again, I'm not telling TWYS is absolutely wrong. It has its positive sides, it's needed in many cases. But you should not value it over clear statements of the artists/publishers, over their rights of ownership and over the common sense.
Updated by slyroon