From a bug report: Broken link to Area 51 "What's Meta" page
We won't show that link at all as of next build.
There are already two links in the Help dropdown that take folks to /faq on Area 51, so a third one really isn't necessary. Not to mention that "meta" as a concept doesn't really apply to Area 51.
So although it's not explicitly stated that this is the desired behaviour, I think we can assume that they don't consider it to be a bug for now, or at least not one that they think needs addressing.