At this point of the discussion, people usually pivot to scope creep: the on-device scanning could scan all your device data, instead of just the data you put on the cloud. This claim assumes that legislators are too dumb to connect the fact that if their phone can search for dogs with “on-device processing,” then it could also search for contraband. I doubt it. And even if they are, the national security apparatus will surely discover this argument for them, aided by the Andurils and NSOs of the world.
As I have repeatedly said: the reaction to this announcement sounds more like a collective reckoning of where we are as humans and not any particular new risk introduced by Apple. In the Apple vs. FBI letter, Tim urged us to have a discussion about encryption, when we want it, why we want it, and to what extent we should protect it. Instead, we elected Trump.