Gold is a liquid asset, He can walk down to the Perth Mint and exchange it for cash immediately. Housing is illquid, you cant simply close out of the position in an afternoon, it also has high exit costs.
Even in times of a liquidity crisis such as the 2008 GFC gold remained a liquid asset, golds value may rise and fall but compare physical metal prices growth against housing since the GFC. Binge credit which fuels house price growth is over, you can see this by how hard Benanke is trying to restart the credit engine but it just wont turn over.
I cant imagine a scenario where gold becomes illiquid especially given Central Banks moves around the world to either stockpile or repatriate their gold reserves, if you can imagine such a scenario I'd love to hear it.
Also the current pension eligibility criteria surrounding the fact that your PPOR is exempt from the income test is around today yes, but it wont be in 10-20 year times after we see the boomers retire, and the unfunded pension model explode in cost.
This will come about by a generational shift in policy stance by the parliament, today we have boomers running the show, and are legislating in the best interest of that societal demographic, once that shifts to Gen Y And Gen X being the primary breadwinners and vote makers in the economy, the legislation will shift to be less favourable towards the boomers. This is true of any government throughout history, their policies serve best the biggest voter demographic, and also the demographic of the parliament.
If you think you will retire at 65 and live out your days in a 1million dollar plus residence with a reverse mortgage complimenting your state pension those days are numbered...