no citizens are allowed on diego garcia and the native population was entirely kicked out. You need a very difficult to aquire permit directly from the millitary to land there.

I'm 99% sure anyone living there is millitary. There were some people fleeing from the sri lankan civil war that landed there and were stuck there for a bunch of years claiming asylum while the millitary tried to figure out what to do with them, but they were sent off the island a while back.