Employees have certain protections, it is true, but so do employers, and both have to work within the law and the guidelines of the job. Employees who are victims of harassment (on basis of sex, race, gender identity, sexuality, etc), that people can attempt to hide behind free speech, are protected; and employees who are perpetrators of that harassment are not, nor should they be.
The truth is not a threat, and telling the truth should never be illegal, but we should be wary of the blind and naive assumption that any of us is indisputably in possession of that truth.