Fallacy, eh? Remember when the DOJ had a secret interpretation[1] of Section 215 of the PATRIOT Act: A federal court and even the author of the Patriot Act itself have revealed that the meaning of “tangible things” was not quite as the NSA had interpreted it, and the massive data collection was not the purposed of the provision[2]
It's a description of what is already happening. But even the first step on that allegedly fallacious slope is an unacceptable one, so that's kind of moot.