Owners using Airbnb aren't in the Accor letting pool, they have no obligation to Accor.
In Hilton at Surfers Paradise, units were sold to individuals with an agent contract in place. So owners are effectively purchasing their units tenanted. Eventually those contracts will run out, and those individual owners will be able to manage their properties however they want.
As for amenities that are owned by the body corporate, like pools etc, anyone can use these as they are owned in common by all unit owners, they are not owned by Accor (Accor may be contracted to mange them, e.g. clean the pool etc, but the body corporate pays Accor to do this).
As for add-on services that Accor may operate by itself in space within the complex - like a Restaurant, Bar or Day Spa, you can still pay to use their services (I think that Sea Temple at Port Douglas lets people staying privately even set up a tab, and pay them directly when you leave).
Again, individual owners at Sea Temple, who do not have a contract for Accor to manage their units' holiday letting business, have absolutely no obligation to Accor. (At the Hilton property, units have been sold to indivual owners with a long term letting contract in place, so it is different.)