If it's not possible for a country to become fascist then is that place still a democracy? Not that we think there will be a sufficient popular upsurge for that form of government but then we think that about communism and socialism too. And that's rather the point of the surmise:
My argument is pretty simple: American fascism cannot happen anymore because the American government is so large and unwieldy. It is simply too hard for the fascists, or for that matter other radical groups, to seize control of. No matter who is elected, the fascists cannot control the bureaucracy, they cannot control all the branches of American government, they cannot control the judiciary, they cannot control semi-independent institutions such as the Federal Reserve, and they cannot control what is sometimes called “the deep state.” The net result is they simply can’t control enough of the modern state to steer it in a fascist direction.
This is, as stated, true of any radical group. And radical can be pretty milquetoast as well. Certainly Nigel Farage and his compadres have been described as such for wishing to over turn the EU order.
Our point being that we do have a reasonable and workable definition of democracy - can we throw the bastards out? And if we can't then we're not. What Tyler Cowen above is insisting is that we can't throw that deep state out - so, are we still a democracy?