Now, that said, I recognize the legitimacy of State and local authorities to enact quarantines. The history of the states reflects the legality of such activity. However, for WA, per this site it seems that, aside from TB, WA has no authority to quarantine people!
I apologize if my commentary to the SE article hinted that I though govt overreach was dandy. And it would appear that in WA, there isn't a legal leg on which the Gov can stand. I'm not an attorney nor do I play one on TV. Your mileage may vary....Good luck.
I consider you a gentleman and a scholar at this point. Our discourse reminds me a bit of conversations that I had with an interesting older gentleman also named Bob who I met in my youth.
My father had run into financial difficulties and my college education had to be cut short so that I could assist in the business that he had become entangled in. For lunch I would eat at the very reasonably priced Royal Fork Buffet which provided enough food for $2 that I only needed to eat once a day. There were senior citizens who ate there everyday as well.
One of them was named Bob and we started sitting together. He was in his 70s and had recently been forced to “retire” from his job as the long time editor and chief of our local newspaper after it was bought out by an out of state conglomerate. I learned more from my conversations with Bob than from anyone who I had met in college.
We lost touch after I was able to go back to school and started working on other projects, but in the mid 90s I ran into him again when I found that he lived next door to a “retirement center” where my new wife was a department head.
At that point although he had almost completely lost his sight to macular degeneration he was helping his son also named Robert Merry with a book that he had written named, “Taking on the World: Joseph and Stewart Alsop- Guardians of the American Century”. He was still able to read with the help of optical devices. He said that he was happy to have lost his sight instead of his hearing because of his love for Mozart.
As you have said the constitutional basis for the current government overreach would appear tenuous at best. I had no idea the actual reasoning behind it could be traced back to the commerce clause as have so many other federal government overreaches.