I guess the optimists/QF management line would be;
Jetstar is a completely new entity. The aircraft & it's performance that Jetstar requires bears no relation to the Qantas fleet.
The pessimists/employee line would be;
They got another "deal of the Century" from Airbus...It's all part of the slow erosion of QF mainline workplace agreements...They don't know what the French word for crap is...
Perhaps Boeing wouldn't trade in the 717's, perhaps they needed any cost advantage they could take over DJ & it's 737NG's...take your pick.
Besides, I think he's practising for his next career in politics...you know, the straight job swap with Anderson!