No idea about this, sorry -- my initial [pure] speculation was O-D pairs that have visa/stay constraints (e.g., South Asian & East Asian citizens flying to/from tourist / study / work visa locations) with limited permission to stay a long time in the GCC, whereas those with US passports / visas typically have greater access to regions & stay viability, as well as many more alternatives to get back to the US (via Africa, Europe, Asia).

I suspect they will rotate the locations day-by-day to get everyone a fair chance, though.