Well, I might be able to answer that........
They might have made the reservation through a special deal intended to attract Americans, Canadians & Europeans there, in order to entice them to buy into a travel club. This hotel is part of Lifestyles, I believe. Cheap Caribbean has deals from time to time, and if you read the small print, it DOES say the rate is only valid for residents of USA, Canada or Europe.
A few years ago, we booked a stay for an unbelievably low price, hotel only, because we were already at our house in DR, so we just drove there (long drive from southwest coast). Upon arrival, we handed over our American passports, and they went to make copies of them. Lo and behold, Mr.AE did not qualify for that hotel rate, because his passport said he was born in DR, and our reservation was void, and we'd have to pay a MUCH high amount if we wanted to stay. I asked for a manager, and calmly demanded an explanation. Upon hearing Mr. AE had lived in the USA since the mid 1970s, he asked for his driver's license. That was enough for them to honor the reservation.
Imagine if we had flown there.....? Their policy sucks.