Copyright law here is clear - once the cat is out of the bag there’s no putting it back in.
What you are actually talking about in this case is clearly trademark, and that's a completely different kettle of fish, which is the only thing that makes your statement even somewhat true. With trademark, you most protect it or you can lose it. That's the whole basis of the kleenex thing from so many years ago.
Copyright is completely different. You can't copyright a character such as Pepe. A particular image or representation can certainly be copyrighted, but that's a different thing.
What this fellow seems to be attempting to do is stuff the genie back in the trademark bottle. If there is any justice at all in the world he wouldn't be able to do that because he made no effort to police the mark when all that stuff was going on.
Mickey Mouse isnt a trademark.
So; there is a statute of limitations here?