an "other" modern – a rootless modernism for the 21st century, a synthesis of modernism and post-colonialism, in which the artist "turns cultural nomad".
In other words - there are no boundaries:
"There are no longer roots to sustain forms, no exact cultural base to serve as a benchmark for variations, no nucleus, no boundaries for artistic language", says Bourriaud
So a 'zombie-Western' seems perfectly reasonable in that context.
Quite how different this is to Postmodernism I am not entirely sure yet, although it suggests to me that instead of being all ironic and distanced about things, kind of sneering as Postmodernism seemed to its detractors, it might be more playful and imaginative and creative for joyful reasons - which seems to me especially relevant as we head into economic meltdown and the supposed turn towards the 'fantastical' as a means of coping with the horror of reality (or something like that!).