The only restaurants that I can imagine / remember within walking distance are the ones in the other hotels around. This is not an area to go for a walk. It is dead at night except for some hotel shuttles and taxi driving around.
When I stay there, I stick to the room service (also because I am generally too tired for anything else).
Unless somebody else has a good idea, I would say that the best option would be for the hotel to organise a taxi ride to one of the villages around the airport in the hope that there is a decent restaurant in one of those.