can they really over-ride my 2nd amendment???
They can over-ride a lot of things.
The Constitution says "Congress shall make no law..."
This ain't Congress- it is your employer.
You have freedom of speech. Stand up in a company meeting, state that the manager is an idiot, that your cat could do a better job of running things, and you think he is ugly. Find out they have a right to fire you.
BTW, remember if you change the state of residence, you need to change your CDL- and you can only have ONE CDL.