I was in Brisbane last time they had an outbreak and the Vic government changed the travel rules when the Qld government changed the lockdown rule so I'm not sure why they've taken a tougher stance this time. But it's pretty simple though:
Red zone (Brisbane): 14 days quaruntine
Orange zone (GC): Quaruntine until negative test.
Idea would be if you've personally been in a red zone you have more chance of exposure than if you run into some people who have been. Works in most cases although a footy match is a bit different. Don't know why the AFL wants to be cute with it though. Just put every game involving a victorian team in a green zone.
Thought process....
Hmmmm can we take the risk?....sure its only StKilda.