2. I think it's disingenuous to imply that Facebook workers - and bear in mind we're not talking about the janitorial staff here, but tech workers who command salaries at and above $100K p.a. - must work at Facebook lest they be destitute. The greatest advantage of being a tech worker is the range of high salary positions available to you. That aside, I return to my previous point about this not being an abstract, culture wars style debate, but specific critique of company actions. It's not politics, but internal politics. Every company has internal debates about the strategic and ethical direction of the company - why not this one?
3. I understand that politics can be exhausting, especially in the highly polarized environment we live in, but I don't think that's sufficient reason to forbid internal critique of any company. Moreover I think the stakes are higher than we are comfortable with - Facebook has already ADMITTED that they provoked the Burmese genocide 2 years ago [https://www.nytimes.com/2018/11/06/technology/myanmar-facebo...].
To flip the question around: what makes YOU think that YOUR personal right to feeling relaxed at work is more important than an employee's right to ensure that they do not work on a product that can lead to mass murder? Moreover, is it really a political stance to demand that you are not complicit in unethical activity?
On a more personal side: I honestly cannot stand when most people discuss politics in the Slack at work. The vast majority of comments are snarky, are unsupported (by data) opinions, or are caustically dismissive of opposing views. It's bad enough when people holding political views I disagree with engage in that behavior, but it's much worse when people I do otherwise agree with do. And it happens in just about equal measure, as far as I've experienced.
Work is already stressful enough without adding to it with political fights.