Under Australian law, the directors of Qantas have a duty to their shareholders to act in the best interests of the shareholders. So if they can lease aircraft which they can operate at a profit, then so be it - and I'm sure that if this meant getting them from Ansett, they would - and in that case the easiest pool of pilots would be Ansett pilots. However, maybe the cheapest source of aircraft is somewhere else (eg. Canada) - so infulfilling their legal obligation to shareholders, Qantas directors may have to take those aircraft over others more locally available. I note that few eyebrows were raised when AC aircraft flew in Spring. Possibly, AWAS, SALE and the other lessors have stipulated conditions on sub-leases that QF can't take the AN aircraft (remembering that AN owns/owned hardly any of its fleet) - whilst such conditions may not attach to AC aircraft. Maybe AC are pricing their aircraft so cheaply as they're happy to get anything return on the assets, the alternative being to park a bunch of airframes they inherited from Canadien which no longer really fit into their Airbus-centred fleet plans.
Sorry, all you AN guys, but commercial factors bigger than just organised action are at work here, and frankly if I was a QF director, I'd be doing my best to stay out of jail (literally) by getting the best deal I could, even if that meant hunting offshore.