At first sight this seems a triumph of international connectivity, but the sci-fi blockbuster transcends cultural boundaries by doing away with the whole problem of meaning and replacing it with CGI spectacle. The director, Joss Whedon, has pulled off an impressive feat in packing so many mythic symbols and archetypes into one movie, while completely castrating their meaning.
Where to begin? The most obvious is that there is not as much a transcending of cultural boundaries as such a movie represents the triumph of a particular national mindset, that of mid-to-late 20th century American culture. The symbols and expressions contained within reflect the values of American pop culture (itself an entity very distinct from the fading regional and ethnic cultures within the United States), not those of a world. Using blockbusters such as this as examples only serve to reinforce the notion that instead of a "global" melding of cultures, a particular national culture has exported most of its value system intact in an insidious form of imperialism.
Although Walter does note that this is not "good," with the comment about "castrating their meaning," followed by the next paragraph observing that "it's arguable that geek culture is really just a response to a lack of culture, a generation who have grown up alienated from any sense of cultural belonging, and are left clinging on to Hollywood product," the problem is not that of an absence of culture (devoid of divergent voices as this mass-pop culture may be, it is still a ritual affair in which some ideals have become reified in the form of superheroes and gadgets that stand in the place of religious/social ceremonies), but that of a particular cultural strain that seeks to homogenize matters.
Walter claims that in the face of this development that science fiction, out of all the other literary modes by which people express their concerns, is the most apt to handle these rapidly-changing developments. To that, I say no. This is not to deny the validity of science fiction's role in voicing certain concerns, but when judged outside the Anglo-American direct sphere of influence, it quickly becomes apparent that science fiction is not the mode of choice.
For example, over the past three decades in Latin America, three distinct yet related literary movements (the infrarealismo that influenced not just Roberto Bolaño, but others associated with him, such as those in the list found within the link; the Crack Manifesto group, which included Jorge Volpi and Ignacio Padilla, among others; and the McOndo group, which included Alberto Fuguet and Edmundo Paz Soldán and several others) emerged that focused on utilizing a hyper-realism to describe the effects of American imperialism/"global" culture on quotidian lives. Their narratives, often acerbic and written as an antithesis of sorts to the magical realism of the Boom Generation, have begun in the past 15 years or so to disseminate into other parts of the world. Bolaño certainly is the most popular of the crew and while he does note in his writings some appreciation for the themes discussed in American science fiction, his main focus is on the world as it is and how the past century has had a devastating effect. Spanish writer Javier Marías also discusses this fragmentation of native cultures over the course of his Your Face Tomorrow trilogy.
I am not as qualified to speak about African and Asian literatures as I am Latin American (I can only read in English, Spanish, Portuguese, Italian, and French at least semi-fluently), but based on people like Gao Xingjian (Nobel Prize winner) and Yan Lianke, both of whom had their works banned by the Chinese government, it would seem that the dominant mode of social discourse in literature is still that of the social-realist novel. Again, this is not denying that China does not have a large SF community – it does – but numbers do not necessarily reflect influence, if the case of dissident literature is to be considered in discussions of "international literature."
While I have no problem with Walter claiming that SF has become more "international" in focus (considering the huge turnout in Portugal earlier this month for George R.R. Martin, it can safely be said that there are active, vibrant communities in several nations on six continents), I do have issues with the unsubstantiated claim that science fiction is the best-equipped to express global sentiments. First, because of my suspicions that "global" is more "imperialist at its end stage" than anything where there is a bilateral dissemination of ideas, and second, because of the rise of a newer style of social novel in which the tensions between the native and imported cultures is a central thematic element. For those reasons alone (and doubtless, there are others that will occur to me later), I have to dismiss Walter's argument for lack of evidence and for arguing a flawed position.