It’s an interesting question whether a debt is owed if a court has not found that it’s owed. If it turns out that a debt is not owed unless a court has found that it’s owed, my description of impeding someone’s free movement (in a car or bike or a boat or an aircraft...) unless a demand for money to discharge an alleged debt is met would be “blackmail” or “extortion” or “false imprisonment” or a combination of those.
The terms of use of an airport, like any other terms, are open to interpretation, challenge, variation by conduct and unenforceability on a variety of grounds. Only courts have authority to decide what those terms mean.
I reckon Qantas should take Sunfish’s advice and cease inconveniencing Canberra airport with those pesky aircraft thingies.
Another crazy idea: Instead of allowing a monopoly asset to continue to be run for the purpose of increasing the private wealth of an individual, re-nationalise the thing and run it as a piece of public infrastructure for the public good.