Private property owners, including private communities, have the freedom to be exclusionary. If they didn't, then "ownership" would be a meaningless concept.
Yet the moment a private community separates entirely from the state and becomes a self-governing sovereign jurisdiction, global immigration egalitarians suddenly claim the moral authority to tell this fledgling micro-nation that it must let anyone in the world live there. In effect, proprietary communities retain the freedom to exclude only so long as they remain under the jurisdiction of an overbearing government they don't want!
Any universalized “open immigration” prescription is incompatible with the freedom to secede and retain the full exercise of private property rights. The attempt to pre-determine immigration policies for every conceivable sovereign community -- big or small, rich or poor, in paradise or in a war zone -- emanates from dogmatic apriorism and eviscerates the libertarian principle of self-determination.
See also: The Principle of Selectivity