In theory, this could be a good thing. I've seen a few covers that very blatantly lifted top selling authors' branding. I'm not talking normal things like stock photos, generic layouts, and common fonts. I'm talking a high level of imitating, copying multiple distinctive details in ways that could only have occurred deliberately. IMO, those are the covers this is aimed at.
In practice, though, they may regret adding this to the guidelines. You only have to look around KBoards to see that tons of authors don't understand the way stock photos work or don't realize that they don't own extremely generic concepts. So there could potentially be a lot of ignorant people reporting their competitors for covers featuring girls with flowing hair and magic in their hands.
I'm not sure how familiar the employees getting those reports are going to be with normal genre cover conventions. To someone who doesn't know anything about it, the above mentioned urban fantasy style does look very similar, and those complaints might get kicked up the chain to yet another person who knows as little about cover conventions as the first.
So, well intentioned idea but maybe not very practical if the final call is being made by someone without experience in design, who has never studied the genre in question.