What would happen if they did region specific maintenance/patching is that the first region to get a patch would force everyone to download the patch. If your particular server had not gone through maintenance yet you would not be able to connect to it because of mismatched versions, so you would then have to wait until your server goes through maintenance. .
Because there is no other software that can handle connections from different client versions.. Sheesh, thats a really silly excuse as to why it cant be done.
Putting my derision aside, if they wanted to separate the maintenance schedule it could be done. If they wanted to have Aussies able to play in Prime time at the cost of some early morning gamers in the US/EU, it could be done.
They have chosen to shaft Aussies because of their own internal reasons and are using hollow excuses about why it is so!