Based on past comments I'd expect the author to have the en_US layout (or something entirely different) and probably - now taking a guess here - even without umlauts.
I'm German and use en_US here, so for ö I'd need to compose a character manually. Which is probably what was mocked (whether that is right or wrong I do not know - I certainly cannot judge the style of writing of someone in his native language, as a foreigner myself).
I'm glad you like the attention, but I have to admit that I didn't waste too much time on that post. Five minutes tops. :)
The 'not an umlaut' part doesn't seem to be relevant though, since we talk about the character composition. 'ö' is the same character both as o-umlaut and as o-diaeresis (I admit I checked if there's a different way to write the latter), so the argument is weird.
de_DE has a character 'ö' on the keyboard, if I use that as umlaut or not is a different problem.
Composing " and o (or whatever you use) produces what looks like o-umlaut to a German speaker - and my understanding was that you were 'attacked' (if you will) for going out of your way to write 'ö'. Whatever that character signifies here.
(I actually didn't know the name diaeresis, but the usage isn't uncommon here. I've driven my share of Citroën 2CVs in the past)
perhaps, but in it i detect a New Yorker magazine-style use of the dieresis to separate vowels into syllables that a reader might be inclined to pronouce together as a single sound, e.g.: reëlect for re-elect.
This is the correct interpretation. But it is actually slightly nuanced; I'm such a bad speller that, even as a native English speaking adult of 30 something, I had to look up no one. Wiktionary has noöne as an "alternative spelling" and I do like The New Yorker...