Generating suspects from mass data collection is close to the definition of a dragnet, both metaphorically and legally. The only difference is it's now being done electronically.

This isn't a case where they've identified a suspect using some specific investigative lead, reasonable suspicion, or probable cause.

Instead, they're using a widespread fishing tactic - a "dragnet" - to gather information in order to generate suspects without any reasonable suspicion. This kind of behavior has been found illegal in the past, because it clearly violates constitutional protections.