Prevented From Working Due To Union Vote (wa)

My wife works for a hospital. She works 2 days per week at one location, and 2 at another. They are both the same hospital system (large, spans multiple states). Her paycheck comes from the large system entity/EIN. The “cost center” they have internally assigned her is hospital #2.

Hospital #1 employees are unionizing. As soon as a vote was scheduled, my wife has been told she cannot work at Hospital #1, something about how since it’s not her home base, they can’t be seen to “take work away” from union members…

The voting unit is defined as “All full-time, regular part-time, and per diem professional employees employed by the Employer at Hospital #1 located in xxx, WA”

1) Is it legal for them to deny her work now? 2) Can she petition to be in the voting class? She is regular, part time at Hospital 1, and employed by the Employer, so I don’t understand why some arbitrary internal classification of cost center would matter. That’s not in the definition.

Thanks.