Currently the missing policy will enter zeros (or any designated score) automatically at the due date, but with assignments that have manual grade posting turned on, those zeros (and the impact to averages) are hidden from students. That means even when assignments have a grace period before the assignment locks, students do not see that missing the assignment has hurt their grade until some time in the future when the teacher manual posts grades. By then it is often too late to catch up with a late submission.
This idea is to include an option in the missing policy to always post the missing score automatically, over-riding any other grade posting policy. This way students can receive a nearly instant prompt about the change in their grade from a missing assignment and take action to get caught up before the assignment locks (at the available until time.)