"It seems like a poorly constructed argument to suppose that creativity is a required element to be the party responsible for creating a copy."
It was. I elided, either deliberately or otherwise (I'm honestly not sure myself), a discussion on the idea that creativity is the standard in the ability to have copyright on something, and thus if you use that as a sort of guideline by choice, then you can make an argument that somebody who isn't bringing any creativity to the party can't be said to be the one who has produced any useful work. Therefore, the question is, if the end-user can't be said to have had any hand in creating the work, who did? Well, the only people left are the developers of the merging code. If it's not legal for said developers to simply distribute the result of the merge, how can it be legal for the result of the merge to appear on someone else's desktop anyhow, if the user didn't really do anything to produce it?
Basically, this asks the question "What is distribution in a world of computing devices, anyhow?" And I reiterate I'm not trying to take a position here per se, but simply pointing out that there is a question here. The ideas of distribution were created before we were all equipped with multiple powerful media engines of our own.
So the copy machine metaphor is not relevant, because copy machines fit into the old paradigm handily. We're not talking about simple copying or we'd already know the answer as to whether or not it is legal, give or take a bit of EULA.
Fair use is unlikely to be even slightly relevant here, for all kinds of reasons. The internet conception of "fair use" does not legally exist, and the legal one seems irrelevant anyhow, since we're stipulating that the end-user has a license to at least the original manifestation of the copyrighted work anyhow. This is the sort of thing I was referring to when I said that step one is understanding there is a problem at all; in my experience most people grappling with these questions get so hung up on the things they want to be able to do that they can't see past those to the underlying issues. The simple truth is that just like pretty much everything else in life, a fair, equitable, and coherent legal answer to these questions may result in you being told you can't do something you want to do, but you can take some comfort in the fact that you won't be the only one, and the result is fair and equitable. (Of course the odds of us getting a fair and equitable legal answer approach zero, especially in light of the fact that virtually nobody has even thought about these issues coherently in the first place.)