The primary observation is one of race. You can visually see that someone is of asian race. You cannot immediately ascertain a specific culture without first learning and recognizing in practice behaviors strongly associated with that culture.

e.g. If you don't know anything about japanese culture at all, you will not know that a person of japanese race who does not get upset when a stranger who is also japanese calls them by first name without honorifics is most likely not of typical japanese culture, nor will you understand why another does get upset in the same situation. Thus you cannot use their culture as a predictor, since you don't have any signals that tell you which culture they're part of. Race is much easier to use as a data point.

Racism only predicts violence and civilsiation inasmuch as it predicts culture, and culture predicts those things better (...)

This is not obvious, nor does it follow trivially from any logical assertions I've seen yet. I've never seen claims either way backed by sufficient evidence to move my prior significantly in either direction.