This is how East Germany worked. You weren't usually harmed for holding non-communist beliefs, but you were blacklisted so that you would never work again.

It's also important to remember that freedom of speech is only protected from the government (which is why your East Germany example is nonsensical). The first admendment says you can stand on a public street corner and yell "God hates Fags" however, if you do so on my property I will remove you.

Mozilla is not a governmental body and (so long as it doesn't violate the protected classes as codified by law http://en.wikipedia.org/wiki/Protected_class) can hire and fire people to project whatever image they see fit.

Correct me if I'm wrong, but blacklisting was done by the government. It wasn't just some business owners that decides they weren't going to hire non-communists. Big difference.