Indeed, but the point is that it's the combination of using GCM and their software that makes this a problem. Because not only does Google know what you're send

Indeed, but the point is that it's the combination of using GCM and their software that makes this a problem. Because not only does Google know what you're sending, but who you're sending it too, because they have both the OS and the network, they can correlate. I mean yes, it's basically impossible to do this. Even if you used a completely free OS, you still have radio chips to contend with etc.