A "special advisor" is nowhere close to a "director" who is making any of the big design decisions. A "special advisor" is just somebody you're running ideas/demonstrations by to get the OK. As Flagship had only made one Kirby game prior, that being a remake, it makes sense that they would have an eye on them like that. It's also the last mainline Kirby title to have Sakurai credited, if I remember correctly.
And while Super Star Ultra is a remake of a Sakurai game, there is no indication that he had any input on the new content that the game introduced.
None of this matters anyway. Super Star (particularly Super Star Ultra) is my favorite Kirby game, so if that's the one that gets favoritism, that's fine by me. Super Star runs surprisingly deep through Smash's DNA, so I think it's fair to highlight it.