It points out a difference between the way, e.g., lawyers and computer scientists see data: lawyers see an invisible attribute -- origin/source/authenticity -- which this essay calls Colour. But computer scientists seem not to recognize this attribute, because it's not really "there" in the data. Raw data doesn't know its own origin. Knowledge of origin has to be applied to the data by a non-machine, because even if a chunk of data encoded information about its origin, there would be no assurance that this information is trustworthy. So computer scientists tend to dismiss Colour as not being anything important, since it doesn't apply to their work with data. But for lawyers, Colour can be even more important than the data itself. For example, simply presenting a fact in court (like, say, the time of sunrise on a given day) is not enough. The fact may be correct, but for the purposes of legal proceedings, the data has to come from a recognized authority or else it is useless.
The author's conclusion is that Colour is important even if it doesn't really "exist." The author gives some examples of ways in which computer scientists intuitively use Colour (despite their alleged blindness to it): cryptography and random numbers. I think this is right, and I think few people (even computer scientists) would argue that Colour is unimportant. But there's a big gap at the end of the essay: what does the conclusion mean for intellectual property policy?
So here is my attempt to fill that gap. I think it would be naïve to assume that people who are against strong intellectual property law are people who want to abolish or deny the existence of Colour. Instead, I think the issue is more about the fact that observance of Colour can't be mechanically enforced. When people do try to mechanically enforce it, things go wrong (because it's a leaky abstraction), and people get mad and sue other people. Thus the desirability of alternative profit models that do not rely on restricted copying, because adopting such models would alleviate an entire class of headaches.