The summit of Sentry box rock is 1673 m I believe so this sighting would have been at least 1600m (cnm says 1606m which I presume is pretty accurate) and Matt's sighting would have been lower at about 1500m I would guess. All of them were males and often small groups of a couple males. Happy to provide any more info about habitat or anything if it helps.
Thanks Ned. That's the highest altitude I am aware that M. harrisi has been found at: noted. I have found M. amabilis at 1600m approx at Rennix walking trail in Kosciuszko National Park.