I don't think it's much of a rhetorical device because you could replace every "you" with "they" and lose no impact. The rhetorical device is a meta one, in the sense that there was something novel about a public communication at one point, but now all communications are essentially public. Another key difference is that the recipient of the open letter would have presumably read it, whereas in this case, Google, clearly, ain't gone read it, or even know about it.