Everything has to be approved by the whole from what i know of it. I loathe Newsome, but he isn't offbase about the chain of command going through the main committee (Neswome is an honorary member as governor, but he does hold significant power).
Cal is the flagship of the conference, not UCLA. The fact that they were not included in the deal has to wrankle the UC system people.
I do know that UCLA's AD is deeply in debt, and i wonder if this resulted in them jumping the gun.