Until you slip :)
Rain doesn't worry me unless it effects my temperature or traction. Those would be my only concern. So I'm wet. I have shelter and can get dry when I want to. Or, I won't have shelter for a while, and wearing myself out in a hurry doesn't make much sense. I guess what the article lacks is, what's the point? Is the point to stay dry because being wet will effect temperature or traction? Great, let's discuss it. If it effects temperature but not traction, run. If it effects traction but not temperature, walk. If it effects both, you need to carefully asses your situation so that you don't die of exposure.
Otherwise, walk and point and laugh at the people running.