They're at a private event, and depending on one's definition of outdoor dining they were technically following the guidelines.* They also weren't going on tv or twitter or on stage at a public event mocking mask wearers.
*personally you wouldn't catch me eating in a space with walls on 3 sides, nor would you find me dining with anywhere near that many people regardless of the guidelines, but that's because I REALLY don't want to bring this into my home. I live with an overweight, prediabetic, hypertensive cancer survivor.