A real issue with large purchases like this is that essentially no Australian (or acceptable OS party) is interested. Some of these farms have been on the rocks and for sale for many years.
Current owners - loosing money daily - often supported by our banks, superfunds etcetc, are pressed to get out. Its a hard policy to legally stop a sale which could stop the pain for current AU owners.
To exist in AU agriculture takes a long term position which very few, including politicians, can fathom
For residential property, also remember for every property purchase for too much money is a seller doing well from the deal and real odds are that its an Australian.