The Phoenix are a New Zealand club that play in an Australian competition. They are not an Australian club and OFC does not allow them to represent the region.
Player registrations are held by the FFA and the players are represented by the Australian PFA. I would have thought that would make them an Australian club based in New Zealand rather than the other way around.
That was my line of thinking too. An Australian club, LOCATED in New Zealand. And I thought the reason OFC didn't allow them to represent NZ in CWC was because they weren't originally playing in the the NZ domestic league; but now they are; and if they applied for dual registration (as the Swiss team are), then...