Nintendo is well-known for censoring games, at least NoA is. It's an on-going process that started in the NES days - NoA wants Nintendo platforms to appear child-friendly, religion-neutral and refrain from any sexual or drug/alcohol/smoking-related content.
I mean, they removed nipples from statues in Castlevania, they removed cigarettes from some enemy sprites in Earthbound, they removed a cross from a hospital not to reference Christianity as well - they've done things far weirder than covering buttocks.