Your boss does not have to let you speak your mind at work.
***Yes, your boss does have to let you speak your mind at work, that right has been upheld by the courts.
Likewise you do not have to work at your bosses location.
***The answer to this is stated before as well: Likewise, the company does not have to set up shop here in America.
Here’s a hypothetical for you. Let’s say DPA5923, Inc. is a company with a crapload of lawyers who engage in shakedown lawsuits against companies like Miller and any other company that takes rights away from US citizens on US soil because, well, that’s its charter and they really felt strong about such things when the owner passed away and gave them a $zillion endowment fund. So, that guy who spoke his mind and got fired, goes to DPA5923 , Inc. and files a lawsuit, signs the complaint and DPA5923 Inc. does the rest and collects the money, giving the complaining party a 10% cut in the final settlement. Did that guy lose his rights when he worked for Miller? No. Does he have more of a chance of having his rights upheld when DPA5923 Inc. is on the case? yes. Does the employer still have the right to tell employees that they can’t carry guns in their private cars on the company private lot? Well, no, because that right is protected in the 2nd amendment in our constitution and it is much easier to see with this hypothetical that the company never really had that right in the first place.
Your hypothetical fails because you are wrong on your assumption that DPA5923 Inc’s lawyers would be successful in their lawsuits. They would not be.
This is not difficult. You do not have a right to a job or to be on another’s private property (ever hear of trespassing). If I ask (or tell) you to leave property that I have possessory rights over (owned or leased or rented etc, etc) and you refuse, you are trespassing and can be arrested and sued for the same.
If I as an employer do not like the fact that you appeared on TV last night in a commercial for my chief competitor, I am in my rights to fire you.
Hell, if I don’t like the way you said good morning to me, I am in my right to fire you. (aside from some contract obligation or legislative measure). Right to work states do not require a good reason or any reason to fire you.
If I forbid weapons on the property I have possessory rights over and you come on my property with a weapon, if I am your employer, I can fire you and if you are invited guest, I can uninvite you and demand you leave.
Your right to keep and bear arms does not trump my property rights just like your right to worship freely doesn’t mean you get to use my pool as a baptismal font.
I am amazed at how many conservatives are only interested in property rights when the owners of the property want to protect conservative interest.