Is racial diversity essential to classroom learning?

See School Choice Made Big Gains During the Covid Pandemic by Jason Riley. Excerpts:

"Pod learning, like charter schools, has been criticized for contributing to school segregation. A public-school official in Atlanta wrote in the New York Times that pods “exacerbate inequities, racial segregation and the opportunity gap within schools.” But where is the evidence that black children need to sit next to white children to learn? Some of the highest-performing public schools in the U.S. are public charter schools with student bodies that are overwhelmingly black and Latino. If racial diversity is so essential to classroom learning, how do children in countries with essentially no such diversity, such as Japan and South Korea, regularly outperform American students on international tests?

In any other use of the word, these pods and charter schools wouldn’t be considered segregated to begin with because nothing besides personal preference is at play. If you go to the symphony and see few black people in attendance, you don’t conclude that the concert hall is segregated. But if someone starts a charter school or a pod in a heavily black neighborhood and nonblacks don’t enroll, school-choice opponents would have you believe that something nefarious is afoot."