A key issue maybe the nominated preferred runway on the Zulu atis. Is it changed by the RAAF Flightwatch agent in a timely manner to fit in with traffic flow or is it an automatic computer generated change purely on the current wind? Dunno.
If the latter is the case then it is understandable how unintended conflicts occur.
One would need strong reasons to operate contrary to the preferred runway even in light winds, however the issue may be that changing after an arriving aircraft has committed to the approach and are unawre of the preferred runway change particularly if the flightwatch person does not broadcast it.