This data was being “compelled” from Google. If Google had told its users that their data might be sold, had sold it, and the government had acquired it that way, this case comes out differently.

In reality, Google simply stopped collecting this data in their cloud, leaving it only on the phone.

Highly recommend (as always) listening to the oral arguments in your favorite podcast player. The specific question of how Google’s T&C’s mattered here came up more than once.