United's media response is correct, if perhaps not completely explained. United's sytem is designed to display the message whenever fewer than seven seats are available in a fare bucket. United's system will show 7 available if there are more available, or the actual number if less. Since websites are normally programmed to pull information from GDS availability, but are programmed separately, showing inventory from another carrier's GDS that shows fewer seats at a time would always display the message. This sales tactic is purely academic, because the number of seats left is immaterial to securing the fare, which is never guaranteed until the purchase is completed.