I must admit I'm a bit surprised both centres will be in Queensland.To be honest the north over south makes sense. Having more days of open skies per year is a productivity matter. Bendigo I'm sure has more clouded days than Mackay and I know Wagga is regularly foggy in the morning which impacts some flights. When you're training new pilots i bet that having cloud free days is preferred to cloudy ones.
Although Mackay has a much larger airport with a 2000m runway, along with the allure of the Whitsunday islands nearby...
Bendigo kind of got a consolation prize in the RMIT flight training school facility.
Theres probably some incentive payment in the deal too (though this is pure speculation on my part and it hasn't been made much of if there is).