For me, a relevant question would be "if an aboriginal did not wish to be in a separated congregation, could they freely join a white congregation." I suspect not.
Actually they can, but in most places where they have aboriginal congregations they are because of the natural suspicion they have of whites and they are areas heavily inhabited by the aboriginals. We had some in our congregation, but they had been raised in the white community and blended in well. Also, the aboriginals have their own way of speaking ... wihch even my aboriginal foster daughter had trouble understanding after being out of their culture for 12 years ... now she speaks to her son in that lingo sometimes to get him used to it also ... so he will be bi-lingual and bi-cultural like she is.
JanG