Adam,
None of those quotes are relevant here. To explain why, let’s go with the example Hayek gave, cosmetics. Let’s say Mr A claimed that some rare poison is a cosmetic. Mr B counters with the argument that the poison is well known to kill someone the instant they touch it, and that a thing that kills on contact cannot be considered a cosmetic. Mr A counters that it doesn’t matter, because Hayek and others say that as long as people decide it is, it is. Mr B counters that the very fact that it is universally known to kill on contact is proof that no one will ever think of it as a cosmetic, because cosmetics are used to look good, and people want to look good when they are alive, not when they are dead.
In other words, B is arguing that from the very definition of a cosmetic, certain things are precluded from ever being considered a cosmetic by people.
Mr A is baffled. “Then what did Hayek mean when he said people decide what a cosmetic is?” B explains patiently that Hayek did not mean that people can decide that what does not fit the definition of a word X can become X by their decision. An apple does turn into an orange because everyone decided it does. [Although they might decide to change the definition of “apple” to include oranges, but that just means they started speaking a different language. If the definition of apple is fixed, people’s decisions cannot change it into an orange].
And once we accept that a word X has a fixed meaning, we can sometimes show by logical reasoning that an object Y will never fit the definition of X. 5 cannot become 4. A deadly poison that kills on contact cannot become a cosmetic. Something that does not fulfill the conditions of the regression theorem [Mises proved] cannot ever fit the definition of the word money.