Why? Google doesn't know who you are chatting with, or even the size of the messages you are sending. Google just sends a "wake up signal and check for messages". That's it.
Your argument on this thread is incoherent. You begin by suggesting that GCM is problematic because it's a component of a larger platform library that gives Google control of Android phones. When it's pointed out that GCM push can be supported without that platform library, your argument shifts: it's the messages themselves that are dangerous. When it's pointed out to you that the messages are empty, you invent a scenario in which GCM push messages enable a kind of traffic analysis that on-the-wire traffic analysis can't already accomplish.
Were this my argument, rather than pointing me to a thread where my points were continually and reliably refuted, I'd take this opportunity to instead restate my argument clearly.
I think you're misinterpreting my arguments because it suits your preconceptions if that were the case. GCM is not just client code. I clarified when someone said the client could be replaced.
I have read this; I don't generally comment on issues I'm not informed on.
Moxie is simply wrong on many of these points, and has been for a while and has had this repeatedly pointed out with no change in opinion. I would rehash this here but you'd be better off simply reading the linked thread and looking at other rebuttals. In particular I remember a 500+ comment GitHub thread on the Play Services issue where Moxie was repeatedly dismissive and rude to those who take issue with the glaring security problems in Signal.