> My understanding is that they used c2rust, and then told the LLM/Agents to make the code more idiomatic rust, while also using the PG test suite as a feedback mechanism.
This is correct
> and thus a fork, and should thus have the original license and copyright preserved)
This is not correct. The Postgres license is permissive. We need to include a copy of the license (which we do in the NOTICE file[0]) but we CAN relicense the Postgres code however we want as long as we meet the requirements of the license. pgrust is a derived work of Postgres, but Postgres allows derived works to be under a different license.