Fair points.
I vaguely recall the previous lease holder having ambitious plans to develop the paddock on the 'hill' behind the control tower, with a new access road, etc, but of course none of that has airside access. I don't have any knowledge of contaminated ground, but given the extensive buildings that were there during the war years, the presence of asbestos is almost guaranteed.
Your right - current available hangar space is effectively nil and constructing new hangar space would be very problematic. I totally agree that businesses at Bankstown looking to relocate are royally screwed, and have few options.
Cessnock have just finished the addition of a bunch of new hangars, and I believe all are already full. Warnervale's new hangars on the western side of the strip are still at the DA stage as far as I know.