Not entirely sure what is meant by "domestic expenditure matter". What is certain is that Australia has contributed well beyond its SAR obligations here and the time will most certainly come when those who do have a direct interest, ie Malaysia, US and China, will have to decide on what comes next and more importantly who pays the bills.
Aus has done well out of this diplomatically, but the law of diminishing returns applies and I'd say that the Aus contribution will be substantially scaled back come "time to regroup, reconsider" or whatever.