Now far be it for me to find a way around this and certainly this is nothing but an exploratory discussion, but I believe the Queensland government say confines of the airport, not confines of the airport terminal.
So perhaps (note, perhaps) if one stayed within the boundaries of the Melbourne Airport boundary, but not within the terminal, one could state one never left the airport.
And if one was to visit this PDF
https://www.melbourneairport.com.au...D-Strategy-Final_High-Res-compressed.pdf.aspx and view page 27 and compare the location of the Ibis with the Melbourne Airport site boundary, perhaps one would have some evidence to back up the claim.
Whether it would pass the pub test (or indeed the QLD government test) is another matter, but the question came up in my mind so I thought it was worth looking in to.
Hope you get home soon
@oz_ally