You misconstrue the meaning of 'la raza' to simplistically mean 'race' which in a general sense it means 'the people'. 
La Raza, baby, indeed. Jose Vasconcelos coined the term, La Raza Cosmica, to express his idea of a fifth "race" (a social construct used to designate groups of people who share similar and distinct physical characteristics) which in Vasconcelos' essay is an agglomeration of all the "races" in the world without respect to color or number who will erect a new kind of civilization called Universópolis. 
His ideal is one to which we can aspire while recognizing that racism--a race-based worldview with prejudice, stereotyping, and discrimination of non-whites, remains an ingrained aspect of American socio-economic and political institutions.
Don't think O'Connor doesn't assume (just like you) the wise old man and wise old woman are white. Sotomayor's Latina is in fact wise since according to studies, white men have the most stubbornly racist attitudes and behaviors.