That, I could guess of one of two things:
1: Nintendo Recommended Universal Citywalk because of the amount of crowds who come through to Denizen, and also via the trust from the Partnership
orr...and this is a stretch, and is purely a guess.
2: Nintendo and Denizen are filming an announcement video for something Universal-related..that has nothing to do with the theme park itself. If they did a tour and it would've kicked off at Universal (ala' Odyssey from Last Year), we would've gotten told of it. And that the only reason why Universal doesn't want their name on it, is to keep the reveal of something Nintendo-related a surprise.
That, is my complete and fully educated guess. I don't have anyone to back up on that, but I am wanting to maybe give somethings that are rattling through my mind.