At issue is probably not so much a Navajo language class, which would probably be taught as an extra-curricular activity, if it was taught in the public classroom at all.

          Ethnic Studies programs that are designed to target Spanish speaking students are tailor made to the system because the students are already segregated by language. To that extent they are "by design" exclusionary.
          We all know how public schools work. If one is in a bilingual-education class for Language Arts, he/she will probably find himself in a similarly populated science class, math class, and etc., simply because that's the only way the schedule can be put together.
          Integrating classes with black students was easier because everyone pretty much spoke the same language.