I think a human would have split the "it's not this, it's that" type of sentence into two separate sentences that could be more descriptive. This is a blog post, not a tweet, so there's no length constraint.

If they wanted to keep it to a single sentence, they could have used a a word like "rather" to act as a separator between moat and wall.

Not to the same extent at all. If you use ChatGPT for a while, you'll see it writes like that very frequently. Humans do write like that sometimes, but not with anywhere the frequency that ChatGPT does it. That's weak evidence for it being ChatGPT.