That's exactly what they did here, I don't see the difference.

This is the difference. This guy took an existing source base, had Claude find specific bugs, then had Claude fix a specific bug which was then reviewed by a person. We also don't know if these changes introduce new problems yet. You are suggesting letting Claude write an entirely new source base. That's light-years away from what happened here.

  > light-years away from what happened here
What? This project is literally an LLM port of Postgres from C to Rust. The name "pgrust" is a hint, if somewhat subtle.

There is also zero evidence a human has reviewed a meaningful amount of the code generated for the port, let alone the original C code from Postgres, given the size/scale of the project and the how quickly it was produced.

They did it on permissively licensed code would be the difference.