This “reform” was mandated by Congress in 1997. It’s part of the Individuals with Disabilities in Education Act. The fact that NYC has been pushed to COMPLY with federal law is a positive move. The fact that class sizes are too huge — for all students — is not a rationale to systematically discriminate against the disabled by segregating them. General education often teachers need and want support to create learning experiences that take into account a huge variety of learners. This ends up supporting all students, not just the disabled. 

New York City also has a very large number of “labeled but not disabled students”: they are poor, and most typically are children of color. This is a pattern that is goes back in NYC — and across the country — since at least the 1960′s. In earlier parts of the century, the students in NYC’s “schools for backward youth” were Italian and Irish. In Romania and Hungary the special education schools are filled with Roma people (Gypsies). In France, it is the African immigrants who are segregated in so-called “special” schools. In Germany, it is the Turkish visitor workers’ children in “special” (read: segregated) schools. 

Separate is never equal. 
Racism is never justifiable.
Sexism is not tolerated.
Why do otherwise progressive people defend ableism? Is it fear of the disabled? There is not a shred of evidence from 30 years of inclusive education research that putting students with disabilities in general education settings with appropriate supports hurts anyone.