I'm also not a lawyer, but as somebody who works in labor -- no, it doesn't have to be about "unions." It can absolutely be about working conditions, if they're in discussions with their coworkers. You're going to be on safer ground when there's a call for concerted action of some kind. You asked about "this" situation specifically, and I don't know enough about what happened to offer an opinion here.
A bit unrelated, but one of my favorite cases on the concept involved Triple Play Sports Bar & Grille, where somebody was fired for a Facebook "like."
I think that's totally related for what I was getting at—great example. Of course you're right that there is almost certainly some level of collaboration here too.
A bit unrelated, but one of my favorite cases on the concept involved Triple Play Sports Bar & Grille, where somebody was fired for a Facebook "like."
https://lizerbramlaw.com/2014/09/09/can-employee-fired-faceb...