As with most "economists" (I use quotes because clearly he's a student) you operate on some broad assumptions based on principles you learned in macro and took as gospel. For something to be considered a currency rather than a commodity it has to fulfill the three roles that we debate endlessly. That said, it only has to meet the minimum criteria. Some currencies excel at one or more but few are best for all three. Take gold for example: great as a store of value through most of history, not so great as a medium of exchange for the day to day transactions since it's heavy and to ensure it's value it must be tested for purity and weighed, as a standard of value it's without compare. I only bring up that example to outline that all currencies have a weak spot. With gold it's heavy, and hard to divide or merge. With bitcoin it's a bit volatile and in the classical sense has no intrinsic value. So it scores low (at the moment) as a store of value (only on the short run, clearly it's over-all track record is nothing short of amazing) and it scores low as a standard of value due to it's lack of intrinsic value. However, as a medium of exchange it is arguably currency 2.0. Never in the history of the world has a medium of exchange like this ever been placed in the hands of the people free from governmental manipulation.

So to the OP I would say while your arguments are well thought out and well worded, they are invalid because they assume that bitcoin must fit your idea of what a currency should be in order to be taken seriously. Is hoarding a threat to bitcoin as a medium of exchange? Yes in the same way that being counter inflationary is. Yet, without the counter inflationary measures it would have no chance as a store of value and clearly if it's being hoarded it's satisfying that use for currency well indeed.