The value of the trick is just in pushing access control outside the situation. Border services generally have extensive but constrained powers - in the US, th

The value of the trick is just in pushing access control outside the situation. Border services generally have extensive but constrained powers - in the US, they're limited in how far from a border they can exercise authority. So they don't get to arrest the administrator directly, or go and confiscate an access key sitting in Edmonton. They can still demand that whoever is at the border arrange for unlocking, and can probably seize the device if they're refused. But the threat "we'll lock you up until you open the device" is potentially legal, while "we'll lock you up because as a hostage until somebody else opens this" has far less merit. (Obviously, none of this applies if you go someplace where actual hostage takings might happen.) If the administrator says "I need physical access to unlock that" or "our firm's policy says I can only open devices once they're at one of our offices being used for billable hours", there's no one handy to apply the wrench to. At that point, confiscate-and-image is as much access as anyone can hope to get.