I agree with you on what their defense would likely be. But with something like this, there is no real way of knowing for sure if companies are infringing on their patents without knowledge of their network and what devices they have. It is entirely possible that they sent this to companies who haven't used these features. The problem is that I can't see prosecutors taking these companies on. I would imagine that a Federal prosecutor would be the one taking them on, which to me, makes it even less likely that it will happen.