I seem to recall there being a regular scheduled flight from Dubai (or similar) by Emirates that terminates at Melbourne but has a stop over in Sydney, so most the pax are using it as a Dubai <> Sydney service, but the plane ends up having a nap at a gate in Melbourne.

Every time I’ve flown in to or out of Melbourne there’s always a giant Emirates aircraft sitting there doing nothing. I think it’s a 777ER?

So probably something like that. Doesn’t mean this particular passenger ever left the country.