Not every mention needs a pull request. Mention @delego [question] (or @delego [answer] — both work) followed by your question in a bound Slack thread, and a runner still picks up the job and investigates the codebase — but instead of opening a PR, it posts its answer right back in the thread.
It's a fast path for questions about the codebase — "where is X handled", "why does Y behave like this" — when you want an answer, not a change.