To add to that, the ruling intentionally did not make a decision on two important distinctions:
1. Forcing you to unlock - in this case, Alisigwe unlocked their phone willingly after being asked.
2. Forensic extraction - the ruling does not give authorities the power to run a sophisticated off-site break-in on your phone without reasonable suspicion.
So if you are a US citizen, and you are willingly unlocking your phone at the border (or you don't have a passcode), the Fourth Amendment no longer protect you from a suspicionless manual search of the phone at the border
But what they can do is confiscate your phone, _image_ it, without the access attempt, and keep the phone as evidence until or unless they feel the need to apply for a warrant for the access.