It's real work in the sense of it involves real effort (work here used as in the phrase "hard work").
But "Real work" for the purposes of this thread is work that is representative of what most people do / realistic for people to have -- and statistically speaking, being a rock star is neither common, not representative of the kind of job most people do.
To recap the argument made:
A: People can't do real work on the iPad because it lacks X.
B: Really? And what about the people that are Y, they don't need X feature.
A: Well, Y is not real work.
What the person A says is not that (a) Y doesn't exist, (b) nobody has Y as their role, (c) nobody makes money by doing Y (and it is thus, their work).
The charitable interpretation, which is obvious since we're talking about e.g. "fighting aliens" (which indeed, is not a "real work" in any sense of the term), is that A means Y is not really representative of the work most people do, and that the percentage of people doing Y is small to not count for the purposes of how useful an iPad is for real work.
