I have two-factor authentication set up on my Apple account. They require that you have a phone number for your device and then you can add additional trusted devices (like an iPad). Here's the thing...if someone steals my Macbook, they can easily defeat my two-factor authentication. Since all my text messages come through the Messages app, this means the code sent from Apple comes right onto my computer. There's no way to disable or "not trust" a laptop unless either I don't include my real phone number in my Apple ID settings or don't use Messages. Am I missing something?