Yep, as soon as somebody narcs to Nintendo (if they even need that to happen, wouldn't surprise me if they proactively search Patreon, Kickstarter, etc on a regular basis for projects that use their IP without authorization), this guy's Patreon is toast and he's getting the dreaded cease & desist letter. If he wants this to be viable, he really needs to take notes from the dev behind
the other game with the very similar concept and title - no mention of that game or anything else to do with copyrighted works that aren't theirs on their Patreon. Of course that also means not offering anything to do with the game as backer rewards, but that's a bullet he's gonna have to bite if he wants this not to get nuked.