As for employees, most work in ‘at will’ environments, which means you don’t need a cause to fire them. That’s a balance against ‘popping off’.
As for the military, they are governed by the UCMJ, and while you have LIMITED constitutional rights, you fall under that area of legal jurisdiction.
I don’t want the courts telling me what speech is allowed in my classrooms. I do not tell them what speech is allowed in their courtrooms, and I do know from at a number of personal experiences that judges hit hard and immediately on any breeches of what they consider proper speech, dress or decorum. The proper and serious level of decorum in a classroom has no less sanctity and importance than a courtroom.
Why don’t THEY respect Teachers and Principals to have the same responsible authority?