He went for a too ambitious update that he couldn't pull off. He got progressively frustrated, less motivated I can guess, more guilty for not releasing in time, and lastly too ashamed to even show up again. I believe thats all that happened and that the guy is alive and well. At least that feels plausible (and painfully relatable). Sometimes this one man self scheduled projects get snowballed to hell as easy as that.
By the way, that never released update was holiday themed (If I recall correctly, he had a lot of trouble with some dress change mechanics, including Santa costumes). Maybe... I mean, of course not, but... maybe... MAYBE he could make a surprise release this holiday???
Dreaming is free...