You have misinterpreted this completely. The linked PDF doesn't mention fiat currency once. NNT says a lot of bullshit, but it's amazing how willing people are to comment without even reading the paper and taking some time to reflect upon it.
No, but it did mention "confidence". My point is that that is the entire basis for money. Deep down, the economy is psychological. You can't "shrug it off" and "remain robust" when the people who make up the economy stop believing in it.