So you would catch the lazy criminals, and maybe even victims of such act, where things were done on their devices without their knowledge... I've read recently about new kind of software, that encrypts your data without your knowledge and then asks you for money to unlock it - wondering how this would play in courts...
It sounds like an encryption suite that had had an included "crytpolocker" gui element would be a hilarious method plausible deniability, and at least make this asinine habit harder. Just randomly generate the BT address so some strangers get paid if the border agents want to try to unlock something they have confiscated.