Yeah, but he's mochi, a processed product of rice... but fuck it, I hate that 'Logias can only be natural crap' rule since the mofo functions exactly like a logia. Plus, candy is a naturally occurring substance in One Piece as we saw after Thriller Bark with that candy rain, and the Boin Archipelago has plants that naturally grow every single kind of food imaginable because fug it.
Make Katakuri a logia and the rice god, LOda.