Based on my experience fighting for the continued existence of a rifle range and club in Victoria that was threatened by housing development, it doesn't really matter how many caveats and sections 173s you place on new housing regarding existing noise etc. it only takes a small but organised group of protesters to get up a petition and local council are obliged to consider such petitions and possibly act to negate existing restrictions. Not sure how councils do that but under certain circumstances, where council have imposed restrictions, they have the power to remove them, so I am told.
Suggest all users of the airfield immediately lodge an amendment to any planning permission for retirement homes requiring a Section 173 be added to the planning permit that all occupants and interested parties are made aware that there is an operating airport nearby and this produces airport noise 24/7, then pick a decibel range that suits. The developers will fight this as VCAT could insist on triple glazing and other noise insulation etc. So now a delay occurs and everything rests in the hands of VCAT. Possibly time to start a fighting fund, "Save our local Airport and jobs"?