Are Australian crewed aircraft required to advise ATC if the approach is to be auto-coupled in good weather or otherwise, even though the intention is not an auto-land?
No.
It seems that way, judging by the wording of the AIP.
No. The AIP merely explains the response that will be provided by ATC if so advised.
Or do crews ignore the risk of signal interference from aircraft taxiing or holding in the critical area while flying the coupled approach.
No. Crews are aware of the risks of signal interference.
This incident would very likely have happened even with LVP in force. The ILS critical area is only protected inside 4NM. This aircraft was at least 10NM when it intercepted a bad G/S signal.
The crew picked it up, the aircraft picked it up (G/S flags), and ATC picked it up.
The system worked.
Having said that, there are other defences that crew can utilise to further protect approach integrity (such as situational awareness, height-distance awareness, not arming G/S until on LOC and satisfied with the signal, VNAV path backup, VSD if installed, RAD ALT awareness, avoiding "dive and drive" techniques in favour of continuous descent, etc).
But clogging up the frequency with redundant "autocoupled" calls ain't one of them.