I'd favor grounding most flights at this point. However, the reason to restrict people from eg Sweden or Ireland or anywhere, is because those people in Seattle are our people (legally, citizenship-wise), which are the ones we should be concerning ourselves with and attempting to control/restrict/observe/test/treat. The US is about to enter mass quarantine, as numerous other countries are. It's better if people from other countries stay outside of the US / stay in their own countries.

And further, it's dramatically better to only have to deal with our own people as a vector, not foreign persons. It's obvious that the fewer people that are infected within the US, the better.