I don't know the law
but doesn't kiddie porn have to prove prurient interest? Like when Jared Fogle videotaped young girls taking showers, while bathtub pics of your children are fine? If that's the case, would someone have to admit under oath that they bought the album to jack off to?
Dude's recreated the cover several times and has a "Nevermind" tattoo. It's all about the money.