Why on earth would Jetstar convert "low time" airbus pilots onto the 787?
Almost every Airbus pilot they currently have today would by definition have at least 750 hours more (and that would be say 350 sectors minimum) by next September/October when I guess the first crews would hit the sim. It will take probably 18 months minimum for the 15 787s to arrive so the lowest crews on the totem pole will be racking up even more hours by the time their turn comes.
I've never seen a JQ crew in action in the simulator but I have no special reason to think that they're of any higher or lower standard than anyone else at other airlines. If anything the fact that the young pilots go straight into the 320 right seat and do lots of sectors would mean their skills would develop faster than someone stuck in the back seat of a 744.
As for "Airbus only" pilots converting to FBW Boeings.....at my old airline plenty of guys did it and didn't seem to be a problem. I heard JQ have plenty of 777/744 captains on their books so I don't suppose getting the Boeing flavour into the place will be difficult.