Can copyrighted source code be laundered through an LLM and come out the other end as a fresh work of authorship, eligible for a new copyright, copyright holder, and license terms?
That is simply creating a derivative work. Derivative works generally are infringing (various exceptions exist: fair use, etc.).
The maintainers appear to be claiming that, under the Oracle v. Google decision, which found that cloning public APIs is fair use, their v7 is a fair use re-implementation of the `chardet` public API.
This is a misrepresentation of the finding in Oracle v. Google. The finding was that APIs are not subject to copyright because they are statements of facts (e.g. function "blah" takes input integer, returns character) and are intentionally published for interoperability (like listing phone numbers in a phone book so that they can be called). How the underlying code is implemented is a separate issue.
Code may not be subject to copyright if the function can only be implemented in a particular way. If there are many ways to do a thing, then the particular way it is done may be copyrighted -and a different way of doing it would not be infringing. Either creating an different way of doing the thing if the original way is known, or by "clean-rooming" -creating a way of doing a thing knowing only the specifications would not be infringing on the copyright as similarity could be attributed to obviousness of the method and copyright protects creative expression.
