If someone makes it to the end of a map without ever having their hp fully drained, then I believe that the game should treat the replay/scoring as if the player wasn't using the NF mod, even if they were.
That way when you put on NF because you have low confidence in your playing, you don't have to replay it without NF once you realize that you can finish the map just fine.
It could also help more skilled players who are trying to get through very difficult parts of the map and are afraid of failing but end up not failing. But those players when trying to recreate the run now without NF end up fumbling under the new pressure of not having the NF safety net, the player gets shaky.
That way when you put on NF because you have low confidence in your playing, you don't have to replay it without NF once you realize that you can finish the map just fine.
It could also help more skilled players who are trying to get through very difficult parts of the map and are afraid of failing but end up not failing. But those players when trying to recreate the run now without NF end up fumbling under the new pressure of not having the NF safety net, the player gets shaky.