Chemistry and biology don’t typically have binary switches. It’s an inhibitor, along with sorbate, which is even stronger. But yes, people who are trying to do it have even fermented colas, with the added challenge of low pH.
I think both the acid and dehydration explanations are true. The reason you’re not supposed to give honey to children less than one is it may contain bacterial spores, especially C. botulinum, that their immune systems cannot cope with.
OTOH, the stuff is acidic. Ages ago I read of experiments done by the Honey Growers Association (or whatever it is called) to see if honey could be substituted for sugar in baked goods. With complete replacement the acidity would interfere with the rising, whether yeast or quick. Just how acid a batch of honey is varies and by measuring the pH and countering it with sodium bicarbonate 100% replacement was successful with nice, moist cakes and sweet rolls.
Unfortunately, the average home kitchen has no way to determine the pH so the recommendation was that the honey replacement be limited to 25%.
That’s bad.
Of course. I’m just offering an example to demonstrate that liquids containing it don’t necessarily fit the OP’s “CAN’T be fermented” criterion. They can, there are just some extra obstacles in the way. (And they’re much less likely to ferment on their own.)
Nah, it just needed aging. 