I have just received a private message from someone from NPWS. In summary, NPWS has officially closed the track, don't add it again. (There was nothing on the ground at survey to indicate it was a closed track.) If it is genuinely closed, then access=discouraged may be best changed to access=no, or possibly use the 'disused:' prefix. My edit had been discussed on the mailing list prior to reversion - I'll send a note back to the mailing list for further discussion.