"Why should Australia and it's citizens bear the social and financial costs"
Because if you don't do it now, it's going to get worse, and you'll get so much people coming over here you won't be able to stop them. First they'll forcibly settle themselves in Indonesia. That will piss off and upset "TEH MUSLIMS" that you're so scared of and hate so much and they'll begin mass migrations here.
Interestingly, the Egyptian empire was almost brought to its knees by the Sea Peoples. Nobody knows who they really are, but current hypotheses are that they were people displaced by fighting or natural disasters.