The only thing I understand is that gold goes up in economic uncertainty. It's a data point.
But personally, I don't understand the rationale.
If we experience a collapse at that scale - who is going to accept gold as tender? Even the bullion experts have trouble sometimes identifying fake gold coins - especially with sophisticated fakes in circulation. Do you really think that an average citizen is going to just accept a gold coin? Also, how do you split it? Silver pieces? I just don't see a future where this is a functional currency anymore. After the disaster - sure, maybe. I guess people can buy it back safely. But during such an event, I think you would be better off hoarding cigarettes, lighters, fresh water, purifiers, etc.