They went in and searched everyone's phones. Unless there's an important detail we aren't being told here, that's unconstitutional. The 4th amendment says "The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."
The important part there is "particularly describing the place to be searched, and the persons or things to be seized." That is in there specifically to ban general search warrants. The idea is the police can't go to a judge and say "We think there is something illegal in a house somewhere in this 500 home neighbourhood, we'd like a warrant to search the houses," and the judge issues them a blanket warrant allowing them to search any home there, and look through anything in said home. That isn't allowed. They have to say specifically where it is they want to search, and what it is they are looking for, and also why they have probable cause to believe that what they are looking for is there.
If you read the article they say right at the bottom "I think it's very questionable whether the 4th Amendment" -- which protects citizens against unreasonable search and seizure -- "allows such an open-ended extension of the search warrant."