"Only a few seats left" refers to Availability, not Seat Maps.
It is perfectly normal to have 38 (or even 138) unassigned seats on the Seat Map and, say, only 5 seats Available for sale (which would trigger that message).
Now you are talking. Is is also legally correct for that particular price range but morally questionable. Since, when looking forward many months ahead I see the same message with almost identical pattern blocks of "available seats" for selection within in this case, CX's website. So sorry for the unsuspecting customer to purchase right away thinking that "Only a few seats left" and then the price drops or when more seats are released by the airline at a more attrative rate.