If that qualifies as a type of legally actionable obstruction, it would seem that intentionally wiping your device before you cross a border and then reloading data onto it once you arrive at your destination would also qualify.
ETA: To complete the threat analysis, and if they seize two devices, one with a password protected key and a LUKS volume without headers? I'll take LUKS.
Because the person made it inaccessible with the intention of concealing it from law enforcement and others. There is still a means to decrypt the data.
All of the actions described in this thread - whether it's decoy passwords, encrypted volumes with headers, burner devices, or wiping data and then restoring at the destination, all seem like they could be construed by law enforcement as a person obstructing their ability to sift through the individual's data.
(But IANAL either.)