The problem had an innocent beginning.  The wife chose to accept United's instruction to disembark ("deplane") without really thinking it through.  She, like most people reading this, obviously wasn't aware that United's  selection process (common to all major domestic airlines) is not at all random or "luck of the draw."  Airlines use computer algorithms that take into consideration a number of factors, one being whether or not a passenger is flying with another family member; this usually is a flag that PREVENTS passengers from being selected.  That BOTH the wife and husband were apparently selected is rather curious.  Had I been in that situation, I would've immediately challenged airline personnel with a question:  Are there any other passengers in coach flying without family members who were NOT selected?  If there were, then a follow-up question would be, "Then why were WE chosen?"