Interestingly, Fable caught the gist and I didn't have to enumerate every Claudism. "Punchy" seemed to be the operative word. My new operating hypothesis is that Claude (Fable in particular) defaults to optimize for concision and "turn of phrase". If we can turn that off, the prose is way more natural.

Claude responded "The arguments and structure are unchanged, but sentences now state claims directly instead of building to a turn of phrase."

I'm OK with colons and semicolons as I tend to write that way.