I think the first one is more likely, but I guess the second one could be a reason too. I remember Nintendo pulled that infamous meme game off the eShop when the person who created the troll face meme filed a copyright infringement suit against the makers of the game for using his creation for monetary purposes without permission. Not related to Nintendo but I also recall some game being pulled off Steam a while back when it was discovered the gun models in the game were DIRECT model rips of the guns from a Call of Duty game.