Yes, at face value, based on what that book is explaining, all forms of money will be worthless. But gold and silver have additional value that goes beyond simple monetary usage, silver especially.
When money becomes as a pariah, we will have already moved into a "safe food" economy. Then food will be used as money, trading it for other needs to get by from day to day. The better the food, with proven superiour nutritional benefits, the more you will get for it. "Junk food" will become food which will keep you alive, although not really nutritionally superiour, and you will be able to trade less for it. I'm not talking about Twinkies, but your typical GMO tomatoes and such. Garbage.
The booze boys AKA Johnny Walker and his cousin Jack Daniels, their neighbor Jim Beam and his daughter Brandy will of course be worth their weight in GOLD as people experiencing hard times desire a little nip now and then to take the edge off of reality. Harvey Wallbanger was evicted for making too much noise at night when honest people are trying to sleep.