I read it that CU had and Agreed Scope before ASX proposed theirs... CU, being a loyal client of ISX, chose to act honourably and work to the contract they already had.
Their position would be invidious considering the dilemma, but perhaps they decided that ASX is not, in fact, a regulator. CU may have concluded that ASX had insufficient authority to usurp the ISX Agreed Scope.
I wonder if ISX is not calling the ASX bluff?
ISX Price at posting:
$1.07 Sentiment: Buy Disclosure: Held