That's the thing: if you ask the Ghost to write as if a frustrated human, it'll happily do so.

LLMs are good at style transfer in fully general sense, they can introduce typos and bad grammar just as easily as it can correct them.

That's fine, and I know that, but I have never heard of anyone doing that to publish something 'more human' on their blog. Not to say that it's never happened, but when I see some pretty basic typos in a blog post that also sounds like actual human frustration, Occam's Razor says it's fair to assume that a human made those typos.