I really liked this bit from the decision: > Third, Wiley and the dissent claim that a nongeographical interpretation will make it difficult, perhaps impossible, for publishers (and other copyright holders) to divide foreign and domestic markets. We concede that is so. A publisher may find it more difficult to charge different prices for the same book in different geographic markets. But we do not see how these facts…
That's why the content industry pushed for the DMCA and used that in the case of the DeCSS case: DMCA as a mean to protect market protection like DVD region encoding. The problem with physical books is that they can't do it. The know it, the court knows it.
But with this ruling, it is now clear that the thing that region codes aim to prevent would be completely legal except for the DMCA's circumvention provision. So in some sense, this is a much more blatant example of copyright owners writing their own laws.