Sorry, you're out-of-date. Federal Appeals Court last year ruled that border guards DO need probable cause to search such things as computers and phones under most circumstances. The only exceptions are circumstances which would also be exceptions away from the border.
The current legality of border searches of electronic property isn't fully settled (see e.g. wikipedia), but the case you're linking is completely unrelated to that issue. The decision doesn't discuss border exceptions -- from the court's perspective, it's a regular arrest and search, and they follow the Supreme Court's recent ruling in Riley v. California (requiring a warrant for searches of a cell phone found during an arrest).