Seems like "parallel construction" where you show you actually understand and can explain the issue independent of an LLM would be the way to go. No need to mention how you found the bug as long as you can explain what the bug is, why it matters, and how to repro.

Lying to get around a project policy you disagree with is immature. They have the right to run things the way they want, either accept their rules or leave the project be.