I am coming in late to the party, responding to the OP. I don't know how it is possible to actually read that photo.
I would like to point out that Solomon collected 666 talents of gold in tribute. It was gold, not foreign currency, so that's an argument against gold being fiat currency.
I also do not care much for far-fetched interpretations that depend on someone saying, "This thing in scripture is an allegory for such and such because I say so."
The value of other commodities goes up and down constantly against gold and silver. US 'fiat currency' deflates at about 3 or 3 and a half percent per year these days, but we can see that gold can go up or down and compare that to wheat or oil going up or down. 'Non fiat' currency, like gold, is not solid and stable. When you buy bread with gold, the value of bread compared to gold goes up and down. If fiat currency is unjust somehow, why isn't gold or silver.
Peter warned that the love of silver is the root of all kinds of evil.