There were C . australis growing in that immediate area back in 1978. Also *well* worth looking for is Todea barbara. There was a nice colony of these growing a bit further up Blue Range Road before they cut down all the Pinus radiata back in the early 1990s. They look like hefty tree ferns, but with primitive looking glossy dark green fronds.
I was noticing the C. australis along the Brown Mountain road up from the Bega Valley this morning, and I strongly suspect this is in fact the same, from the way the dead fronds hang, but it would be good to get a close up of the fronds to confirm. It's good to see multiple C. australis thriving in the Blue Range, though oddly I've not seen them in the Brindabellas or the Tidbinbilla Range. I'd be surprised if they weren't there.