>>537468543
https://web.archive.org/web/20030610004527/http://www.nintendo.com/games/gamepage/developerinfo.jsp?gameId=312
>This interview was conducted before Kirby 64 was released in Japan, and was originally posted on Nintendo Co. Ltd's website.

>Have you seen Kirby 64: The Crystal Shards yet?
>I haven't played it yet. Actually, I've been trying to avoid even taking a peek at Kirby 64. I'm afraid I'd start making comments which might conflict with the vision of the development team and create confusion.

What I take from this is that Sakurai didn't look at 64 during development because he didn't want to influence Shimomura and his team too much, and planned to play the game after release.