This ranking now seems like he will be penalised for that because no matter what formula they are using, by its very nature it’s a ranking system that benefits those in the top part of the ranking
But that's fair surely - if someone is a very secure grade 7, they should be awarded a 7, whereas if someone is a 6, could get a 7 on a good day and the teacher puts them at a 7 with a low rank, if the schools results are moderates down, it should be the insecurely graded ones that move down.
Don't forget being the bottom ranked in a grade band would only mean they're moved down if the whole cohort is moderated. If the exam board is happy that the assessments look secure no one will be moderated down.
Effectively it's the same process as grade boundaries which move each year. The kid who gets 56% which was enough for a grade 6 last year, might well find the grade boundary changes to 57% the following year so they just miss out.