Isn’t there some “middle letter” support group he can join? It won’t necessarily solve the problem but it will help him deal with it.
You could all shave your heads ort something to show you support him.
Well, if you’re tired of tiny violins…and if you really want to cause some office drama—
Rearrange the nametags in order of job titles. Or better yet, arrange 'em by salary. 
But then you’re gonna need a big violin.
Nah, add a title that says “Arranged by Importance” and watch the fur fly.
How about “By Order of Appearance” like in a movie? Watch everybody start caring when people come to work!
I used to work in a lab that had three zones - a clean room, the main area, and a “dirty” room. It was designed this way to reduce cross-contamination, because we were testing clinical samples, and a mistake could, for instance, lead to someone getting unnecessary chemotherapy. Each area had its own set of color-coded lab coats: yellow for clean, blue for the main area, and white for the dirty room. So far, so boring.
At one point, though, we had a medical doctor do a rotation through our lab, and she put up what can only be called a “massive hissy-fit”, because she was a DOCTOR, and therefore she DESERVED to wear a white lab coat at all times! No yellow or blue coats for her, because she might be confused for one of the peons! So she spent the whole time there wearing her white lab coats, unaware of how silly she looked to the rest of us.
Put a blank line between each name on the list. Now everyone is at the top of their own list.
I love this idea. Not that I or anyone else will actually do it, but it would be get the point across in a way that co-worker could hardly object to, since it solves the “problem” that he claims is driving his actions.
Thing is, we don’t actually hate the guy, so we don’t really want to embarrass him or anything by publicly pointing out what an idiot he’s being. (Yeah, I know, it’s HIS actions that would be the ultimate source of embarrassment, but you know what I mean.) He’s invariably friendly and cheerful around the office, and within his niche area, he’s quite competent. His technical specialty is uncommon, so he brings steady work to our firm. Overall he’s a positive asset for our company, it’s just that every so often he gets a stick up his ass about some insignificant thing. This particular episode, I believe, sets a new record for the insignificance of the thing. I also believe this record will be hard to beat.
Zsofia, I really like that idea.
Just get rid of the “in” and “out” magnets. You put your name up when you come in and pull it of when you are out.
Can you get a snowflake-shaped magnet special for him?