And the rest that aren't codeshares?
(A) I refer to point (2) in my previous reply.
(B) I have already noted that I am not an airline employee and lack inside information. However since you are inviting me to speculate - even insisting on it ...
Flights between Bali and Australia fly southwards.
That is a major point of difference. Most flights head north, north-east, north-west or, in a few cases west.
Some reports have stated that the ash clouds have been blown south.
I was discussing this with an acquaintance whose daughter was stuck in Bali.
I asked if she had looked at other flight options. She replied that she had looked at all the options - and then listed flights to every Australian capital.
I suggested she look at flying via KUL or SIN. Anything to head out of Bali in a different direction.
This may not be the reason. I have acknowledged that it is nothing more than (reluctant) speculation.
However I am absolutely certain that, whatever the reasons - however risk-averse, however misguided - they are commercial reasons.
The spectre of political correctness is not to blame.