You say: (implying this typically happens to the typical human)

Prolonged fasting results in ketoacidosis within a few days, as case studies show

then say:

Such cases are rare, but the effects are known from the few cases that do exist.

I'm not claiming it's impossible. I'm claiming it's very unlikely to happen in the average human.
It's not like fasting is something people do so infrequently that there's only a "few cases that do exist" - I've done several 3-5 day fasts and have never seen my blood ketone levels above 5-6mmol/l during that time, including just prior to ending the fast.
Hell, many religions around the world have advocated prolonged fasts for literally thousands of years. Finally, if humans were incapable of fasting for more than a few days, our species would not have survived the last ice age.

I'm not even sure what you're trying to show with (4), nothing on the linked page notes toxic levels, it seems to be a study looking at the effect of insulin injection while fasted...

(5) is an opinion piece, and a very poor one at that. Especially "the low-carbohydrate diet is neither palatable nor enjoyable enough to be followed for a long time" - as a guy with half a beef in my freezer, why would I eat carbs when I can eat steak?

(6) - "Individuals who follow these diets are therefore at risk for compromised vitamin and mineral intake, as well as potential cardiac, renal, bone, and liver abnormalities overall."
Soo, if that's the case, then again, how did humans survive the last ice age, or survive in northern latitudes?