A 5th grader who got an 800 on math on the SAT is amazing! The rest of his scores are amazing as well!

I believe that you/he misunderstood the essay scoring process. A 6 is the highest score you can get on the essay. Two scorers score the essay thus the two scores (6 and 6). If the scores differ by more than one point, a third person also scores it to determine where the score falls. In any case, he had no room for improvement on the essay from his first score.