I don't think the guy who posted this works for Canonical at the moment. If he does, his launchpad page is very sparse compared to other employees. I'm not saying that to disparage him in any way, but because it would make it incompatible with a not-invented-here syndrome.
I think Mir should be looked at as an independent project now. I might be wrong, of course, but that's the impression I have.
Even given that Mir is independent, it sounds like people are continuing to work on it because they have already invested in working on it. I've yet to hear of any users.
I agree, I'm not saying it's useful in a sense other than academic/historic. I was only reacting to "NIH". I guess you might be arguing that Mir continues as a consequence of nostalgia from an original not-invented-here syndrome.
I won't argue with that :-P
That said, if the guy who posted this is not employed by Canonical (like I speculated), and has _never_ been employed by Canonical, I would like to further speculate that either (a) he's doing this in order to specifically gain favor with Canonical employees and increase his chances of employment there later, or (b) to increase his chances of employment at any of the "big Linux players", or (c) to increase his knowledge of the X/wayland ecosystem and C coding in general.
All of which sound like good investments on his part.
Anyway that's speculation upon speculation, obviously, but if I was a professor at a generic I.T. bachelor/masters, this is exactly what I'd tell my students to do in their spare time (and if they could weave it into related classwork, all the better obviously).