Very few of the many who responded to your question took the time to read it properly. I understand quite clearly you are not talking about separating the two in order to hide something -- you are talking about the fact that if CBP is seizing a laptop in order to search it, even if we accept that as legitimate, it is the HARD DRIVE they are claiming a right to search, not the laptop itself (unless they are claiming you have secreted drugs inside it somewhere, an assertion they could not claim being unable to verify on the spot, and then either arrest you or let you continue with your drive-less laptop still in your possession).

I agree with the response of one of the few posters who did actually make the effort to actually read your post -- it does indeed make some sense and you could of course argue that as you have separated the container and its contents that they have no reason to hold on to your laptop. But as he pointed out, this would be virgin legal territory, so we cannot say for certain what the outcome of a case would be in which CBP asserted the right to seize it anyway and you counter-sued. In fact, even if you didn't separate the two, I don't see why a lap-top seizure victim shouldn't be able to assert that only the hard-drive should be held. It's been established by case law that searches can only go where the suspicion goes -- e.g. if an agent finds reasonable suspicion you are smugglng drugs in a secret compartment in your vehicle, and they have already searched and cleared your suitcase and found it free of any contraband, they could hold on to your vehicle while they conducted a more thorough search, but they would have to let you take your suitcase with you.