Bottom line is that 'your business' isn't any longer yours.
The Hooters example was discrimination against someone because of their gender, making the issue one of a protected class. Religion, age and ethnic origin place one in a protected class, which only means that they cant be fired for those reasons (this is where it really is hard to fire someone even with cause). Unions also make it almost impossible to fire someone with or without cause.
However, political affiliation does not place one in a protected class, making their employment at will. You can chose to believe that unless you are in a protected class you can successfully sue your employer for firing you, and good luck. In the real world employers are allowed to fire people just because they dont like them. Those people may sue, but they lose.
Political affiliation is a protected class in federal employment as of 1998 IIRC.
Bubba wanted to make sure some of his sycophants stayed in the gov't.