Thanks, that was the impression I had when I was there. It was suggested to me today that they were likely to have been planted, so I was just curious if it was common knowledge one way or the other.
There are a number of sites on Mt Majura and Mt Ainslie where the species occurs - I think Michael Doherty mapped those (not on CNM). One group on Mt Ainslie consists of an old multistemmed tree surrounded by younger trees of the same age group; maybe this sighting https://canberra.naturemapr.org/sightings/2458309. I suggested there was a fire in the early eighties that damaged the old tree/s and triggered germination from seeds.