To approach it from another angle, if I were laying out a room, and was asked to place a receptacle up high for a wall-mounted TV, I would install another one at whatever-height-matches-the-rest-of-the-room from the floor, even if it was directly beneath the TV receptacle.
Additionally, if 'directed' by the customer to omit the lower one (for asthetics, I guess) and he insisted, based on the upper one meeting NEC spacing requirements, I'd comply, but only with the agreement that he'd pay for me to install one later if the inspector required it.
My alternate suggestion would be to adjust the layout to accomodate placing one receptacle within six feet of each side of the TV, if the desire is to have blank wall below the TV. However, people often place low furniture below the TV for A/V gear anyway.