It sounds like it's less "segregation" (misuse of the word) and more "grouping" of similar students with the intention of making their school-life better.
If I was only one of a handful of White English kids in an school in an Asian country, I'd probably want to be put in a class with a few others, not distributed equally like we're tokens.
It's all explained in the article quite clearly:
... the policy was born from conversations with recent graduates who said the school could “create greater opportunities for connection and support.”
He points to a passage from the school’s handbook that states: “Research points to the academic, social, and emotional benefits to being in a classroom with others who share racial, ethnic, linguistic, and/or cultural backgrounds.”
An NYC-based educational consultant with a focus on minority students said Little Red School House’s proposal is “the lesser of two evils,” explaining that often when there is a single black or Latin student in a class — especially history and literature classes where discussions can turn political or personal — they can feel isolated and uncomfortable.
“The intention is to make students of color feel that they are a critical mass and have a voice,” the consultant said, adding that a handful of other schools, including Bank Street on the Upper West Side — which has students break into self-identified “affinity groups” four times a year for 45 minute classes — have experimented with similar policies, though to a much lesser degree.
Is this the minority parents complaining or the white parents virtue-signalling?