Sprite,
It was established much earlier in the thread that it is one's duty to obtain up to date weather information throughout the flight to aid in ones decision making. The ATSB recommendations only indicate that pilots now need to get the weather themselves, as opposed to having it given to them as was the case in the past. But that, however, is not at all what we are debating here.
You have not provided any new information there to support your claim that an alternate is legally required should minima fall below the alt. minima during the flight. The quote given from 73.2.10 is a clarification of how the visibility should be applied when two visibilities are given. If you read 73.2.9, once again the evidence suggests that the AIP is refering to the planning stage of the flight.
73.2.9 Due to the continuous weather watch provided by TTF, the 30 minute
buffers required by paragraphs 73.2.7 and 73.2.8 do not apply.
Flights which will be completed within the time of validity of the TTF
may be planned wholly with reference to the destination TTF.
The ATSB report is simply a report of what happened, because a PAN call was made. It does not in any way indicate that what the pilot chose was required.
No-one here would criticise the pilot of that flight, or anyone else, for declaring a PAN if they genuinely think that the safety of the flight has been compromised.
There seems to be a very large percentage of pilots in Australia that overcomplicate every rule that they read, and always assume the law to be more restrictive than it actually is. You can't argue with these people, because if you do, you're some sort of irresponsible cowboy.
I'm going to take a leaf out of Gundog's book and retire from this thread, as its been going around in circles for quite some time now. I have provided a couple of strong quotes to support my case (in particular, the CAR1988 reference), and am yet to see any solid evidence to the contrary.
From the CAR:
239 Planning of flight by pilot in command
(1) Before beginning a flight,...
All regulations on alternates are contained within this section.
I look forward to hearing from Izdat on the CASA take on this.