It isn't binary, either good or bad. Maybe it attracts the best people (and I note you had to say "perhaps" since you are just speculating), but it definitely raises the costs of doing business quite substantially, which means less ability to hire, expand, or exist at all. That's not speculation, that's the entire purpose of regulation like this; the government directs you to spend money in this manner or go out of business, no third option.

You must also consider that the California system as a whole, which includes its regulatation system, has become unaffordable and California faces the task of either tearing some of it down or raising taxes to make up for it, and one way or another you must account that negative to that system, too. It's easy to "politic" away the problem of unaffordability for quite a while, just as we have done, until suddenly it produces a result far worse than if we had done the putatively-inferior-but-actually-affordable thing in the first place. Unaffordability is not a political matter, it's an objective one that can't be argued away. And I emphasize the "has become" because that is now past tense, it has happened.

The author is sticking to the facts of the cost of doing business, rather than speculating about IMHO rather nebulous possibilities of "retaining the best people". I think a rather good case could be made that whatever positive effects such regulation has, it passed the point of diminishing returns a long time ago. I don't live in California, and I do not feel a pressing need to move there so my boss stops beating me. (Yes, that is rhetorical, but the basic point stands. At some point regulations just add cost and not much benefit.)