Ha, good luck trying to argue that. The Gogo website makes it clear that there are separate services for phones and laptops. Their website automatically detects what kind of device you have, if they make a mistake then it's their problem if they don't offer you the means to correct it. But if you deliberately circumvent their system to save money, then you're committing a fraud.

I'd urge you to learn a little more about the law if you think that a UA string specific law is needed, or even a computer-specific law. Intent and personal gain are more an enough.