The New Yorker likes its umlauts (or, as less than two minutes of research on Wikipedia told me, technically it likes its “trema diacritics”). They pop them on words they simply don’t belong in: coördinate, reëvaluate, zoölogy, etc. Sure, I understand the idea is to emphasize that the second vowel is voiced after a pause (glottal stop? I don’t actually know anything about phonology), but seriously? We’re one step away from vacuüm. And two steps away from skiïng.
No real point to this rant other than the fact that umlauts should be preserved for words where they belong, like doppelgänger or schön or Blue Öyster Cult.