I am not living in the US and am not aware of these laws, but they do make sense in the wording above.

In the story these comments refer to the driver had no real place to stop his truck and I believe he was justified in going slow on a rainy/slushy road in a heavy track on a decline.

If you are driving slowly you should be letting others pass you whenever possible. I'm actually quite amazed that you actually need laws for that (not that our drivers are better in any way, it is just common sense).