Welcome to the sandbox,
Not only is this common , it is encouraged to organize based on nationality. The locals have their majlis where they meet every evening. The "second tier" Arab nationals usually have their own group quite often leaving the Egyptians out. Western expats are also sub divided, Eastern Europeans being considered as inferior . If you are black , Pakistani or any sort of Asian don't expect to get any sort of respect right away unless you have lots and lots of money.
This isn't EK , this is just how the gulf has operated for years and years. Things ain't going to change anytime soon .