I think he was alluding to the constitutional right to privacy, which is something we do have.
The number of people in the car (i.e. whether another passenger could have been using the phone) shouldn't affect whether you have the right to the privacy of your communications and personal data on your phone.
The number of people in the car (i.e. whether another passenger could have been using the phone) shouldn't affect whether you have the right to the privacy of your communications and personal data on your phone.