So I read "Are Cryptocurrencies Currencies? Bitcoin as Legal Tender in El Salvador" from what you linked, and it really seems to come down to: Don't trust the system (don't trust the government is how I interpreted that) Don't understand Bitcoin
Which interestingly, refutes that idea that money comes from the government, although I do agree that taxation in one commodity and only that commodity (or government stamped item) gives that thing enough value to pay taxes, but because your taxes get cheaper as time goes on (inflation destroys the value of the stamped item) I find no incentive to hold such an item for any longer than absolutely required.
I also am not a fan of the assertion that "Money’s essential feature is to be used as a medium of exchange", rather, it is one of its features. The feature that was missed in the paper, is the store of value aspect, because people try to save money to purchase something else at a later date.
No paper I have read, has been able to refute the idea of holding on to anything other than a governments currency and only converting it when required. Inflation guarentees the "price" always goes up, except when measured with other assets like when housing is priced in gold for example. Instead, they have only been able to confidently assert that this means a governments currency is a medium of exchange and therefore money.
Lets speak to Gresham's law for a moment, which you have referenced. Of course I'm willing to pay someone who insists on accepting trash, using trash at the time of purchase. If a business wishes only to accept cheeseburger wrappers (I'm American), those can be purchased with something of value very easily at a moments noticed and transferred to the desirer, but by no means would I start saving up cheeseburger wrappers as a result, because I know that it does not have long term prospects. Over time, that business will require more and more cheeseburger wrappers for what they're selling and so its smarter for me to hold say silver which I could much more easily trade for many many cheeseburger wrappers as time goes on.
There is this strange psychological occurance, by which people differenciate between investments and money. It would make sense that an investment is something which costs money in the short term but will grow and generate wealth in the long term, but that has been perversed. Like I said with houses measured in gold (that is the median housing price as to be independant of population growth in specific regions), one might think that buying a house is an investment, but according to the chart, houses are liabilities. (source: http://pricedingold.com/us-home-prices/). but they still seem to fair well enough against inflation and so you see houses is where the rich store wealth, therefore, houses are money, not investments. The liability aspect is all the repairs the house requires, but if the house is rented out and you can adjust the rent to inflation, then it becomes an asset. (the wisdom of using a house as a store of value also depends on how much the value of houses is propped up by debt within the debt cycle.)
I could go on about the S&P 500 being a flat line against gold or saving money in gold or silver until making the purchase for which something is being saved, but I'm at the point of writing an article so I'll just conclude with, Bitcoin doesn't do what Keynesian would expect and write it off as not being money, but the way a Bitcoiner understands money is fundamentally different and our goals and measurements for successfulness are also different from what the central bankers will try to portray.