I skimmed the paper, so I may have missed important details, but, there is a factual claim here which is mistaken. "Irrealism" has been explored, in significant detail, by Nelson Goodman in his
Starmaking, but it is not clear to me he would accept a "virtual world" metaphor.
It's also not clear to me what is gained by saying that the world we experience is "virtual" - what does that even mean? As I see it, a virtual world is almost a world, but not quite, several aspects are missing, think of videogames or VR headsets: that is virtual.
Such views tend to leave the interpretation open, that this virtual world is mistaken or skewed. But if we had no "virtual" world, we wouldn't have any world. In order to be able to see or experience anything, it needs come from a perceiver, unless you would bet that the objects in the world are themselves conscious and can experience each other. Something of which we have no evidence.
"Virtual" thinking is OK, I guess, as a heuristic, but not much more than that. I think the more traditional, Schopenhauerian (and Hume, Locke, Descartes, Kant, etc.) view of the world being a representation is more accurate, it's the way we react to the stimulus of the world, without claiming that it is a simulation. It's simply the way things appear to us.
We may postulate - sensibly in my opinion - something "behind" objects that anchors them, but this "behindness" is no more "real" than what we already experience, it's another aspect of the world, which helps us make sense of experience, as I see it.