I think you're misstating it a bit. To my understanding, California law doesn't say that if any of those conditions are met, the employer automatically owns the

I think you're misstating it a bit. To my understanding, California law doesn't say that if any of those conditions are met, the employer automatically owns the IP. Rather, it says that if none of those conditions are met, any contractual provision which would otherwise cause the employer to own the IP is invalid. If one or more of the conditions are met, the contract (and other laws, such as work for hire) govern, and the IP may or may not belong to the employer.