That’s not what he said. He wants to get rid of kids being tracked into gifted kindergartens because a) it’s ludicrous and b) testing four year olds is just a roundabout way of finding the kids with parents who got them a tutor for kindergarten entrance exams, and the replacement metric of getting pre-k teachers to pick them is not much different. He argues that kids don’t need to be shuffled off to special schools until more like 8 years old, when the 2nd grade testing happens.

He also obviously doesn’t believe it’s wrong to adjust learning to capacity. He just has the less popular view that this can be done without tagging kids at four years old and changing their lives. (He probably also understands that there’s plenty a brilliant math kid who belongs in a standard English class, or even in remedial classes to deal with a concurrent learning disability).