Isn't it possible to fabricate the timestamps on commits and then push them up all at once? If you're planning on literally checking that the commits are publicly available for a certain amount of time, that seems like it would needlessly punish projects that someone worked on offline and then happened to push up once it was completed.

What about hardware projects without a code base? Those are fun too and deserve front page

I suspect automating "code base over time" metric is tricky. Not everyone will be using git or a vcs and somethings dont need a codebase to be shared.