To split survivors by race is as arbitrary as any other splitting method.
The question of whether the act of mentioning or pointing out race as a description is in itself racist seems to still be open.
Racism could be described as the act of applying special meaning to the race of a person, either negative or positive.
The act of dividing the survivors by race isn't racist. To assume that dividing the survivors by race has any special meaning, or that the survivors of a certain group will act differently to another, could be described as racist.
The fact this season of Survivor has caused so much controversy tells us that to many race does has special meaning.
Which as I said, is racist...