I definitely agree that it's a lot better than just making replays always public or always not-public. But there exist other possibilities that would be worth testing, such as, for example, instead of a public time and a non-public time, make all replays non-public for a number of days, say, 10 days. So, if you post a replay at the beginning of the race, nobody will be able to see it until 10 days later. If you want to make sure nobody will see your replay until the race is over, just post it when the race is less than 10 days to end.
This is just one thing that could be done. There are so many other possibilities. I don't say change it, but it'd be good to sit to consider all the possible combinations before starting the next year. Maybe there's a new amazing idea, just to keep on adding new spices