... does an employer really have the right to tell employees whether or not they can exercise their free right to make political contributions?

Of course, the corporate vs. individual rights issue goes far deeper and wider than political contributions. If you worked at Pepsi at a high enough level, you could get your arse fired for drinking Coca-Cola, and vice-versa.

Oh, well, that's why I am in my own "bidness" ... I have had enough corporate bullshit and backstabbing to last me a lifetime, although I did do fairly well while I was at it: CIO of $15 billion company. Yay Me! LOL