Wirelessly posted (BlackBerry9000/5.0.0.822 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/102)

Seee, that's the first problem, looking for rationale

It was likely to separate the domestic passengers from the international ones (never mind the logic or the absence of it), because the ones continuing to Dubai should have had their passports exit-stamped at PNQ already.