Arny, there is no reverberant soundfield in that room, and simply increasing the coverage area of absorption as a percentage of wall surface is not the solution. That applies only to large acoustical spaces and then only to addressing the reverberant noise floor well beyond the critical distance (of which there is none in a small acoustical space...). What you have in a small acoustical space is localized behavior characterized by modal behavior below about 300 Hz and specular reflections above about 300 Hz.
And employing absorption in that manner om a small room simply results in a fast track to a dead room.
That said, do to his topology without looking at any of the rest of the setup, he might consider broadband absorption on the rear wall and setting mounting surrounds to the sides of the seating area and allowing the surround sources themselves act as the ambiance. (But that said, do to the close proximity to the sources, there is not going to be an adequate response (at least to the rear left) possible.
They would be better off just running the 3 front channels.