On the same webpage, this organisation, claims to be is now run by Aerospace Australia Ltd who says this
Aerospace Australia Limited is also a member of the not-for-profit group headed by Aerospace Maritime and Defence Foundation of Australia Limited.
The corporate purpose of Aerospace Australia Limited is to promote the development of aviation and Australian industrial, manufacturing and information/communications technology resources with respect to aviation, aerospace and defence.
This event is advertised as a public airshow, but ASDU website now denies this.
It goes on to say that all invitees and performances are controlled fully by the RAAF.
That explains a lot. Avalon is just a big defence circle jerk. No wonder there is no GA component, the RAAF hates GA.