This is without doubt the most politically loaded NLRB in American history. They've pretty much abandoned even the slightest pretense of fairness with Labor; they are in the tank completely for unions. Even granting that, this is a pretty outrageous move: 

NLRB lawyer Thomas Quigley, noting that this only happened at two of five facilities, argues that to make all of the workers stay out of the nursing home until “until we sort out who the evildoers are is unfair. It’s collective punishment at its worst.”

Is the NLRB doing anything to catch the “evildoers”? No, according to the company. “Both the Board and Union oppose providing Respondents with any type of discovery that would help [the nursing home] identify the participants in the sabotage and the extent to which Union officers and other members may have encouraged it or were otherwise complicit in it,” HealthBridge told the judge in a court filing

So, you shouldn't punish the innocent with the guilty, but we're not going to do anything to help you identify the guilty. As I said, not even the pretense of fairness.