Why do we need legislation? Formation of unions is protected by freedom of association in the 1st amendment. Not sure why we need another federal bureaucracy to intervene in the negotiating process. Not sure why we need the whole all or nothing union voting process. What if 33% of employees want to join the union? What if managers want to join? Why can't they just join?
Because after WWII, when the US workforce had a lot of leverage and the power of unions was high, the US criminalized a bunch of things that unions do in exchange for a few token concessions.
Freedom of association isn't a serious right in the US. Every town has "gang member" registries. At least we don't criminalize political parties like the UK or the rest of Europe.
The fundamental purpose of the constitution is to limit government overreach. Limitations on individuals and corporations are enacted through legislation. Those limitations (in general) are necessary because without them, people with the most power abuse the people with the least, until there's a violent uprising. Today's legislation exists because of the last violent uprising in response to abuses of corporate power. Removing it wholesale, without replacement, invites that bloody history to repeat itself.
Wanna tweak it so managers can unionize? Sounds fine to me! Wanna make union membership optional through federal law? That's gonna be a fight.
That NLRB page does say that "supervisors who have been discriminated against for refusing to violate the NLRA may be covered", so I wonder if that might apply in this case? I suppose there's no way to tell from the outside, but if _I_ were one of those fired managers, I would be looking into it...
[1] https://www.nlrb.gov/about-nlrb/rights-we-protect/your-right...