IMO appearing to be heavily-bulliable is unironically a decent part of it.
Phase is far from the only vtuber agency where the CEO is very much a public figure and a part of shaping the company's image, hell, Yagoo probably was that before Fish even started, but Sakana, from my personal impression at least, tops the ranking of "can take the most banter from his talents". Outsiders see the girls openly chastising Sakana and making fun of his turbocharged autism and shape their perspective of Phase's inner workings based on these interactions - which is obviously incorrect, as from what we've heard of Phase's actual inner workings, while Sakana is turbo-autistic, he's also fairly ruthless and goal-oriented, and nobody in the company actually forgets that he's the boss.
But the facade of "the girls are free to just shoot shit and banter with their CEO" is too alluring for many to look any deeper.