G, FB, TW are all private companies, no different than your small business.
Do you allow one candidate to post a sign in your front yard but not the other? Would you be pissed because the local, state or fed government came in and said you can't post any signs or you must post all signs?
The ONLY difference between your business's front yard and Google's front yard is the number of people that can see what is displayed.
I am NOT defending Google, but the first amendment does NOT protect a private citizen from speaking things YOU don't like.
The first amenedment only stops the government from restricting your speech as a citizen, it has no power to stop a private citizen from saying whatever they want however they want.
So, explain to me how we're supposed to balance this? If FB wants to tell republicans they can't post signs in their front yard, the fix is to leave FB and make it so they fail in the marketplace. If you don't like that attitude they have, make it hurt in their check book.
If you say that too many people don't care and my fix in the marketplace wouldn't work. Then I suggest you stop watching porn and football, and maybe educate your friends and neighbors in the matters of real freedom and liberty, and what must be done as individuals to keep said freedom and liberty.