Coming from and Enjoy Gaming rep...

It was removed due to an error in the ESRB rating embedded in the code. ESRB re rated the game as Teen with descriptors and Nintendo took the product out of eShop because the parental controls were then wrong. The code has now been altered and resubmitted to Nintendo for their normal checks before it will be re released on eShop in the not too distant future. Thank you for your interest. I hope this answered your question.

Thanks to Julia for the heads up!