Yes, it likely should be a criminal act, and it may even be covered by one. But it should not be a violation of the CFAA. In your Geek Squadder case, you gave

Yes, it likely should be a criminal act, and it may even be covered by one. But it should not be a violation of the CFAA. In your Geek Squadder case, you gave him access to the computer. He may have used that access improperly, but he did not increase his access through any illicit means. It is likely a crime, but not one that should be covered by the CFAA. Your plumber case is a much different scenario. Also definitely a crime, but you did not grant him access to the machine. So it's possible that the CFAA should cover that, but I don't have the knowledge required to answer that with any amount of certainty.