EDIT: Whoops, typed for too long.
We do what we can to encourage open discussion about images, and at the same time artists reserve all their rights when they post on this site.
Someone talking about their own creation on someone else’s artwork, however, is not something that we encourage, and no one has a right to do so.
If an artist asks some other person to stop using their artwork to promote their derivative work, then I hope that other person will stop. If they won’t, then we will do what we can to resolve the situation.
Remember, if the artist doesn’t want their work associated with someone else’s derivative work, the artist’s copyright comes first. And they retain all rights.
So if someone is using someone else’s art to promote a derivative creation, and the original artist wants nothing to do with it, we listen to the original artist.
Simply put, the artist has the nuclear option of deleting their artwork from the site if they don’t want their work used in derivative works, or used to promote something someone else is doing.
And we’d rather avoid that.