Poettering commented, the issue is now closed. https://github.com/systemd/systemd/issues/41085#issuecomment-4053443496
Asking for detection of security vulnerabilities from an LLM is one thing though, that one I could consider useful, but the real question is code and documentation generation. It does seem that for now, the bot usage isn't auto-merging PRs, which does alleviate some previous concerns of mine if reading that right.
But, in AGENTS.md it does mention "docs/CODING_STYLE.md — full style guide (must-read before writing code)". https://github.com/systemd/systemd/blob/main/AGENTS.md
They do require disclosure in the project also of LLM usage. But this does imply that LLM contributed changes are considered welcome, so we will probably see more of them, but I suppose at least they should hopefully be marked appropriately.