Tony Stark arrived to the party. Why? Because he got an invitation, and was a fan of the free booze. There would be plenty here, and it was sure to be the good stuff. Besides, Stark Industries did all of the IT work and software design for Hyrule's hotels, and he wanted to keep the good rep with Zelda's father.
So, he was there. Acting very Tony-ish. Drinking champagne, flirting with the ladies, sampling the appetizers. Though, he spent a good deal of time checking and re-checking his smart phone.