Then how do they explain Washington's higher 8.2% rate?
You should read the comment in the original post (http://www.tonywright.com/2009/should-you-move-your-startup-...) by user abscondment.
He contends that the data that Tony wrote is uncertain because there is less data available on Washington than California, so he propses using a confidence interval of at least 97.5%, which puts California in the lead. Lowering the confidence interval even more would give California an even greater lead.