If the former, I still think that the vast majority of production software has metrics/unit tests that could be attached and subsequently hillclimbed via RL. Whether the resulting optimized programs would be considered "good" depends on your definition of "good." I suspect mine is more utilitarian than yours (as even after some thought I can't conceive of what a "terrible" proof might look like), but I am skeptical that your code review will prove to be a better measure of goodness than a broad suite of unit tests/verifiers/metrics -- which, to my original last point, are only getting more robust! And if these aren't enough, I suspect the addition of LLM-as-a-judge (potentially ensembles) checking for readability/maintainability/security vulnerabilities will eventually put code quality above that of what currently qualifies as "good" code.
Your examples of tasks that can't easily be optimized (image fidelity, song quality, etc.) seem out of scope to me -- can you point to categories of extant software that could not be hillclimbed via RL? Or is this just a fundamental disagreement about what it means for software to be "good"? At any rate, I think we can agree that the original claim that "The LLM has one job, to make code that looks plausible. That's it. There's no logic gone into writing that bit of code" is wrong in the context of RL.