High achievers / high earners moving into lower achieving / low earning schools seems like a good thing regardless.
Of course, this is a dynamic system, and if enough high-scoring kids migrate to less-rigorous schools then the advantage would be diluted. But at the same time, kids who previously would have gone to that less-rigorous school will now be measured against a different standard, since their school would no longer be one that has a very low average SAT. Basically, it's complicated, and there are weird incentives at play.