He refused to provide his password because they were on a fishing expedition. The did get a warrant. The warrant should have specified what evidence they were looking for. The problem with getting a warrant to search your phone for nothing specific is it will lead to searching your home or car for nothing specific. I would have to assume the phone warrant stated specifically what they were looking for, and not just any evidence to support a hunch. Your right to privacy is bigger than any one case.
If it’s an improper warrant, challenge the warrant. If it is not specific enough, courts make that decision.