You need to take up your issue with an Australian Migration Lawyer. If you undertake and complete an aviation tertiary degree in Australia you may be able to obtain a bridging visa enabling you to work and gain experience in Australia for a limited time. I doubt as a newly minted pilot you will be permitted to remain long enough to accumulate 1,500 hours. Bear in mind there are hundreds of other Australian newly graduated pilots also looking for work and you may find it extremely difficult to find pilot employment.
The eternal new pilot dilemma - how to get to 400 hours for employment opportunities and how to get to 1,500 hours for possible airline employment. There is no guaranteed pathway and the road is tough. Many make it; some fail. As a low hour pilot graduate there is no possibility of employer sponsorship in Australia.
I would have thought you may be better off undertaking an airline cadet program with an airline that is able to provide employment opportunities at the completion of training? There are airline specific colleges in Australia, China Southern in West Australia and Qantas in Queensland. The Singapore Airforce is also based in Western Australia and Queensland. Various Australian Universities offer aviation tertiary degrees.
It sounds like you need to undertake a lot more research on temporary migration to determine a viable career path.