This is an argument used constantly by AI advocates, and it's really not as strong as they seem to think.*
Yes, there exists some prompt that produces the desired output. Reductio ad absurdum, you can just prompt the desired code and tell it to change nothing.
Maybe there is some boilerplate prompt that will tell the LLM to look for security, usability, accessibility, legal, style, etc. issues and fix them. But you still have to review the code to be sure that it followed everything and made the correct tradeoff, and that means that you, the human, has to understand the code and have the discernment to identify flaws and adjust the prompt or rework the code in steps.
It's precisely that discernment that the author lacks for certain areas and which no "better" prompting will obviate. Unless you can be sure that LLMs always produce the best output for a given prompt, and the given prompt is the best it can be, you will still need a discerning human reviewer.
* Followed closely by: "Oh, that prompt produced bad results 2 weeks ago? AI moves fast, I'm sure it's already much better now, try again! The newest models are much more capable."