Do you think Chinese people are thinking "I sure hope Facebook doesn't comply with the government so that I can keep not having access to it and therefore keep not being silenced by it. Ah also, I really just wish Baidu/Weibo/Wechat/etc. would close shop already because they are censorship enablers.". My bet is that very few people are and while they're probably unhappy with the censorship in general, they are happy to have access to some form of social media.
Yes. The principle of free speech is a fundamental American value and it should be upheld by American companies.
For them to sacrifice core values for access to a foreign market is unethical. I have no expectations that Facebook will be ethical, but the point of having values is that you stick to them. Otherwise they are just preferences.
If they don't take a stand in China then they won't take a stand in America either.
The Chinese people couldn't possibly care less whether they have access to Facebook or not, and the ones who do already have VPNs.
There's a big difference between creating a morally neutral tool (like Facebook itself, which may be used for evil, such as in cases like cyberbullying) and creating a tool for an explicitly immoral purpose to be given to an entity which will obviously use it for immoral purposes.
What Facebook is doing is deeply unethical.