There are certain legal differences between 'selling a product' and 'distributing testing hardware'. It's not clear to me that classifying the Explorer Edition

There are certain legal differences between 'selling a product' and 'distributing testing hardware'. It's not clear to me that classifying the Explorer Edition as the latter would hold up in court because of the method of distribution, but that seems to be the theory that Google is working under. And it's perfectly possible that it would hold up. If it doesn't hold up, it has no legal force. Though they can still close your account and make you take them to court over the software side of things.