What are you going to do if someones culture really does have a significant measurable impact on their learning performance? Tell them that their culture sucks?
Well, you do it to the taliban, don't you? Granted, their approach to schooling and teaching isn't perhaps the main reason, but it's cleary on the agenda, and often discussed.
So there's at least a precedent for telling someone their culture sucks. There's even a precedent for shooting at them... (Not that I'm saying that the cultures discussed here are in any way shape or form similar to the taliban, but there is a precedent for speaking up about it).