There is no political order or rule of law without an enclosure. A political entity needs to have boundaries. This is why all discussions of “global citizenship or democracy without borders” are silly claptrap. There can be no polity and no political subjects without borders. All that can exist in a borderless world is alienated, constantly competing individuals who vary in their degree of adaptation to fluidity.
From the beginning, the idea behind sovereignty was that the political sphere could be constituted in such a way that it didn’t have to be ruled by the demands of the economy. This might be a fantasy, but it’s an important fantasy because it shows us what our aspirational goal could be. Once the nation-state is ditched in favor of “borderless society,” we leave aside that fantasy and accept that economy is all there is.
Brown doesn’t doubt that the nation-state is over. Hence, she has no use for any attempts to shore it up. This must make her work frustrating to those who aren’t ready to say goodbye to it. On the other hand, she isn’t a cheerleader for globalization either, so those are are into inane transnationalism won’t find much of interest in her work either.