The aikikai site above claims it "is the only Australian organisation to have grading authority from the Aikido World Headquarters in Japan".
I know it used to be the only Australian organisation to have grading authority from Aikikai Honbu, but I'm pretty sure A.K.I. and one other that I can't remember right now also have grading authority at present. They might want to update their website.
Agreed- All my Dan grades including my Godan were awarded to me in Australia under the direct authority of Aikikai Hombu, beginning with my Shodan nearly 30-years ago, and I am not, and have never been, a member of Aikikai Australia. To my knowledge Aikikai Hombu has awarded at least 200 hundred Dan grades to teachers and students in Australia who have no connection with Aikikai Australia, including my own students when I was teaching there.