In an interview in Next Generation issue 2, Miyamoto was asked about his involvement in Donkey Kong Country which, interestingly, the interviewer attributes primarily to Miyamoto, referring to it as "your game". His response only refers to the character design process, translating hand-drawn images to CG, and it's unclear whether he had any involvement beyond that. Perhaps he was trying to distance himself a bit from it, if the rumours of the Yoshi's Island and DKC internal rivalry are true. Hey, maybe that's why Nintendo passed on acquiring Rare in the early 2000s. lol
Having read through that NG interview numerous times over the years, honestly, it wouldn't surprise me if the statement the OP is referring to was made by Miyamoto, just because some of the responses are a few degrees spicier than you'd expect from such a prominent figure at Nintendo. If it's true, then it is surprising that it wasn't removed at the request of some Nintendo PR person prior to printing; but both that interview and the OP's quote are from an era where, if Miyamoto so much as smoked two cigarettes while leaning against the cubicle of a programmer working on some first party title, he'd be credited as a producer, so maybe he felt he had some latitude to speak his mind. lol
I like DKC, btw, although playing it on a modern display is pretty painful. Those dithered CG visuals really benefit from a consumer CRT with fat scanlines.