>As always, the most ethical thing to do is to just ignore any anti-LLM policies and not disclose anything
How does this have anything to do with ethics? Its their project not yours, they can reject your PR for whatever reason, including you using LLMs for developing that PR. Also they're not assuming autonomous agents submitting PRs. They're saying that they do not accept PRs where any part of the thinking process was outsourced to a LLM.
Even if you disagree with their opinion, the ethical thing to do is to not interact and move on. Not to try to sneak in your LLM assisted PRs without the maintainers consent.