Part (a) says NOTAMS are to include information required by Reg's, Act or Commonwealth Law and (b) information affecting "safe air navigation". Commercial considerations do not fit into any of the requirements to issue a NOTAM. I would suggest the airport users challenge the NOTAM Office to have this withdrawn.
NOTAM Office: 02 6268 5063
Fax: 02 6268 504
Wouldn't the non availability of a runway, for whatever reason, affect 'safe air navigation'
It is a legit Notam as far as affecting air safety is concerned. Whether or not they have a right to make the runway / runup bay unavailable is a different matter.