Yes, and perhaps even more so. Through the petition clause of the First Amendment, the Constitution's Framers recognized that those who ask government to address unfairness face an extra risk of retaliation. Through the petition clause, they flatly prohibited any restraint on petitioning government for redress of grievances. At worst, courts will treat a petition as speech and require that it pass both the public concern and balancing tests before protecting public employees who present grievances.
However, different courts have different views on whether the public concern standard should apply to retaliatory dismissal of a public employee who files a petition.
With a labor grievance, the government can hardly claim that the employee was being disruptive, since the employee is following the government's own policy on how to file the grievance. Hopefully other courts will see the light that the right to petition is not limited to matters of public concern. Until then, many labor activists will suffer retaliation without a remedy.