This is what I suspect. I don't think the article is confusing, but I could only present the info I had from the ruling. Hence why it is not entirely clear what the customer thought he was getting, and since Asus didn't respond, they didn't get a chance to point out he didn't read the technical stuff correctly.
Still, as pointed out, even their international site doesn't explicitly say you need to buy some extra kit to see stuff in 3D - it's hidden behind language like "Nvidia 3D vision 2 supported".
Not everyone is super tech savvy and while that seems obvious to us, the customer may have thought it was 3D out the box, as with something like the 3DS, or perhaps that it came with the required glasses kit.