probably just nit-picking here but if the gold is being used to secure payment, then presumably the contract says that you can't take the gold out if you are not current on your payments. Like one of those garage-like storage units, where they'll seal it and not allow you access if you're far enough behind on payments, and sell off the contents if you don't make it current. It doesn't mean you don't own the contents of the unit.
Responding to your other comment, yes there are a lot of relevant difference with taxes, compared to storage fees or construction liens or other ways that property can be used to secure a debt. Presumably in an AnCap society (feel free to correct me, AnCappers!) someone could create a subdivision and sell off plots of land with contractual obligations about paying for the shared roads and sewer and whatnot, with the property being used to secure that obligation -- so if someone didn't keep paying, they could be compelled to sell the property. The obvious difference is that it's voluntary, but this kind of arrangement wouldn't mean that you don't own the land.
If you can sell property, and pocket the net proceeds, you're not the tenant you're the owner.