I think you're somewhat missing my point. Whether the nation's wealth is spent on submarines or aged care, it is only created by a sufficient element of the population being out and about labouring, paying taxes and buying goods & services.
The point being you could drop the subs and have significant budget savings. The Australian domestic market has surprised me how resilient it has been to the pandemic, and not from printing money. Strong switch to delivered goods and services and the housing market going the reverse of what was expected, all shows Aussies have lots of excess cash available to drive the local market. Just because aviation is tanking is not sinking the country, like said before the basics of mining and our generated national wealth is so far protecting us. People are not spending money in foreign countries and instead on domestic produce, meaning more local wealth is staying put in Australia.
If you asked me last year what the economy would be like this year with continued lockdowns etc, I would have agreed with the doom and gloom.