Perhaps I didn't express myself well, but I think they did.
The point is that even if gold has no significant inherent value1, it still makes sense for us to behave as if it does. Suppose I have food, need shoes but don't need medicine and someone else has shoes, needs medicine but doesn't need food. If there exists some form of currency which I can confidently accept in exchange for food with the knowledge that someone else will later accept said currency in exchange for shoes, then that saves me the bother of looking for someone who has shoes and needs food; as long as people broadly agree on how much food, shoes or medicine can be exchanged for a given unit of currency then barring the scenario RTP mentions I can always rely on people giving me what I need in exchange for currency. The point of my earlier post is that the two given properties of gold make it ideal for use as currency. Of course it's arbitrary how much value is assigned to a kilo of gold (within the limits of what's physically practical), but that doesn't matter.
1 Which I would not agree with, as it happens - in fact gold's physical properties make it very well suited to use in jewellery. Of course jewellery isn't as important as food, shoes or medicine but then neither are music, books, alcohol or any number of other things that people are nonetheless willing to pay for. But that's beside the point.