It could be any of the 40 or so Anthela species for which no photo or description of the larvae has been published. @Clarel : can you rear it in captivity to get the adult moth to discover the species ?
Geez, I’d love to, but I saw it on a bush walk in a national park and am now 200km away. In any case, I think I’d need a license to collect from a NSW NP but I haven’t looked into the details.