It is true that "racist" is often thrown around in everyday life as an insult. However, that doesn't impose any limits of the possible definitions of the word as used in social theory and analysis. If we analyze racism as a social formation and identify specific characteristics of the social world that supporting that social formation, the fact that we're using the term differently than people in everyday life is irrelevant. It's okay that a word has a different meanings in different contexts!
Miles