It's been a few years but I learned from management school that there are certain freedoms I had an an employer when firing an employee. Essentially, I could fire any employee for any reason any time EXCEPT those that were expressly forbidden by law.
Having an employee manual or set of established rules made the job easier but was not required.
More specifically, I could fire an employee because I told him I didn't like his Mickey Mouse Necktie but he insisted on wearing it after I told him not to. His attire had nothing to do with his job either. Yes, I could fire him for that as just cause. If I didn't have a set of rules in writing, then it was expected that I HAD to give a single warning of "my unwritten rule" to solidify my case if it went to court but not necessarily required. I could actually fire him for no reason given other than empoyment incompatibility, in other words we didn't get along. Things may have changed since then but that is the schooling I had.
The constitution does prevent the government from making a law that prohibits free speech and it is assumed that everyone has a right to free speech like that Mickeymouse Necktie but likewise, the constitution does not require an employer to make a job for those who wear a MickeyMouse Necktie.
In the case of certain restrictions, If a particular employee interviews for a job who has certain personal qualities specified in the law, such as race creed, sex age etc. Those specific qualifiers prevent me from discrimination on that employee for both hiring AND firing. In addition, I would not be permitted in asking those questions. Later I recall they changed the law a bit to allow me to question race for certain government requirements but I still was not allowed to use that information in hiring and firing decisions.... thin, I know.
A simple vague NDA signed by an employee at time of hiring may forbid that person either discretely or indiscretely from violation. Firing that individual for violation of the NDA is grounds, IMO, based on what I was taught.
However, if a person states public information such as the posted example, that In his opinion DirecTV has NFLST which many people find great, then I would have no grounds for firing him on the basis of an NDA he signed. Having my security people determine that an employee with NDA has, under a disguise of a false identity, (screenname) posted insider not made public information, then without warning, he would be subject to discharge.
I feel bad for all, and apparently there are several, who have lost their jobs from DishNetwork. But, before you feel you were unfairly fired, carefully look at your individual situation and objectively rate whether you have violated any of the employer's rules for employment. Carefully look at what they did and see if they violated any of your rights. If you have a clear cut case- then take them to court. An attorney will often work on contingency if a good case.
I was once charged and had to go to court for firing an employee, he claimed for getting hurt on the job. This would have been an OSHA violation on my part if true. He had lied to his lawyer. In court I submitted all the documents regarding his case and won the arbitration in the state of NY. I did not hire an attorney but represented myself. What I fired him for was not his getting hurt on the job but rather his failure to return to work after his physician released him to return. He decided to take a vacation for 22 days. I simply listed he vacated his position and my company showed we paid for all his medical from the injury until his doctor released him.