"it probably scrapped the multiple git repository of Windows leaked source code. In which case it would ABSOLUTELY undermine the project's ability to say it's a clean room implementation"

If an LLM model has been fed leaked code, then that is a general problem for that model and for its use for anything. Singling out its use for an open-source project and denouncing that as a potential problem while otherwise keeping quiet about it just makes no sense. Just take legal action against the model if there's anything plausible to warrant that, don't weaponize it against open-source projects.