I'd bet it was just one of that endangered species, a CO
star 
on a full fare ticket who dallied to long at the club before moseying down to the plane.
Maybe the "service agent" thought that your non-elite companion on a cheapo ticket would be more at home in the back of the bus with his/her ilk.
It sucks, but money talks. Call 1-800 WE COULD CARE, give 'em an earfull, and let us know what they say.