

You’re mixing up corporate personhood and the CEO’s own personhood. He isn’t the corporation. Ultimately, he’s just an employee. There’s no good reason for the board of directors to pay him if a machine can do a better job while costing less. I’m not sure why you might think that wouldn’t happen.
You might want to read more about corporate personhood. It doesn’t mean that the corporation is considered by the law to be a person, or that whoever or whatever performs the duties of the CEO is by definition a person. It means that a corporation, despite not being a person, has certain rights usually associated with people. For example, a person can own property or be sued. A cat cannot own property or be sued. A corporation is like a person rather than a cat in that it can also own property or be sued. There’s debate about exactly which rights should be granted to corporations, but the idea that a corporation has at least some minimal set of rights is centuries old and an essential part of the very definition of what a corporation is.