It’s raising the bar for doing these searches. Essentially saying some government investigator can’t go “oh well if we had this data we might find something interesting, so let’s get the data.” The court here is saying these geofenced searches smell a lot like such a fishing expedition hoping to find something interesting.

Rather you should have evidence that a specific person did a specific thing and need to conduct a search to find additional evidence of said person doing said thing.

The 4th amendment protects US persons from the government just doing generalized searches in hopes that it will turn up useful info. You have a right to privacy from the government unless the government can clear a high bar showing probable cause that you’ve done something wrong.