I'm lucky that I'm in a place financially and career-wise that I can just quit and find a new job if I disagree with my company's politics, but many others don't have that luxury. Their choices are either to talk about it and try to get their company to change, or feel awful keeping quiet.
Is your claim that we really need more corporate control over politics in the US and less citizen participation?
The fact of the matter is political conversations have high risk of annoying/frustrating/alienating their participants. To have these conversations at work is just making employees less productive and asking for a controversy.
I dare say it might be time for some employees at Facebook to pause and think about how their work may have an impact on the world.
I agree that there's no need to bring up politics in the break room (or worse, during active work) and risk alienating people. It's a bad idea, just like talking about or advocating for particular religious beliefs.
But if your company is being politically active in ways you find unethical, I don't think it's reasonable to expect people to just put their heads in the sand, ignore it, and get their work done. And not everyone has the luxury of quitting a job whenever their don't agree with the company's politics.