The leaves look a bit narrow for A. iteophylla. It could be A. boormanii or A. juncifolia. Both of these have been found on Farrer Ridge as garden escapes, so there could be similar escapees on Mount Ainslie.
I asked Greg Baines about this and he said , it looks like A. linearifolia to me, the straight pods and bent tips to the phylodes look correct. A. linearifolia is a common in gardens, landscape plantings and old reveg projects around town. It is naturalised in a few places.