the U.S. customs can't [under normal circumstances] confiscate your computer. what they however [sadly] can do, is power it up and ask for your password. you HAVE the right to not handover the password, but again, they [sadly] have the right to take an image of your hard disk for later "use". of course, this can take hours - so your point still stands.

other then that - customs is always a grey zone, as you're officially not yet on U.S. soil, so they can [sadly] pretty much do whatever they please...

but hey, what would you expect from a rising fascist regime with such a great propaganda machinery .)