Because it’s not about supporting QF/VA. The entire point of IFAM is to get the exports to their destination.
You are quite right but that is also a very narrow view to take. Consider the multi-billion dollar submarine fleet the federal government is buying. They are spending billions more to build them in Australia in order to support Australian industry. The main goal is to get a fleet of new subs but the secondary benefit is to support the industry in Australia. The IFAM should be looked at in the same way.
In a circular economy the money that you put into Australian companies and employees gets recycled back to support many more Australian jobs, it has a multiplying effect. Once you send that money offshore it then does nothing for the country.