I don't see any way to remove the code block option either completely or restricted within editor permissions. Selecting never for "can use headings" still leaves the code block option available after the Paragraph option regardless of editor level. Same for selecting never for "can use content boxes".

Consequently changing the available editor in Member groups is not an effective option . This seems odd since, at least on my site, many if not most regular Members will be confused with it.

Any way to disable it? What is the intended use case for non tech Members?

There is indeed no way in which to do this at present. Thank you for your feedback