Subject: Re: Washington, Oregon, California
Yes, Trump will take them to court,

...and fight it out over this:

No State shall, without the Consent of Congress, lay any Duty of Tonnage, keep Troops, or Ships of War in time of Peace, enter into any Agreement or Compact with another State, or with a foreign Power, or engage in War, unless actually invaded, or in such imminent Danger as will not admit of delay.

Article I, Section 10, Clause 3 of the US Constitution.

The question will come down to if whether or not this 'compact' of some of the dumber health professionals in the country somehow supersedes federal authority (or not). If it doesn't, they can play with each other. If it does, they can't.