Overwhelmingly the most common case is people accusing others of posting in bad faith merely because the other's view is so far from their own that they can't conceive of them having it for legit reasons. This is a reflexive reaction—a feeling that we all need to recognize and stop ourselves from expressing in raw form. When people vent it into comments, the result is either war between the two sides, or, if one side outnumbers the other, an ugly mob dynamic in which a few people are ganged up on for being different. Those few either leave, or they become resentful and break the site guidelines badly themselves, as a way of lashing back against unfair treatment. All these outcomes poison the community.
Not to pick on you personally—it happens because of how human nature reacts to the weird conditions of the internet, which we're not wired for. It is hard for all of us to grasp how large and diverse the community is, and how divided it is on divisive topics. Nationalistic themes are some of the most divisive ones, and unfortunately are growing more common these days.
I'm familiar with that account. Their posts, and what private data we have, are completely consistent with who they say they are: a former Google employee and startup founder who has lived in both China and the U.S., has a Kubernetes war story, opinions about Python, Go, PHP, software deployment and so on, and who is frustrated by comments about China here because they feel many commenters don't know what they're talking about. It's natural that someone who lived many years in both countries would feel that way. Some of their comments have broken the site guidelines, but that's a separate issue—and who of us wouldn't, having our integrity attacked outright like they have?
This is clearly a case of somebody being singled out for suspicion because they have different views, formed by different experiences, than others here. When users do that, it puts us in toxic territory. Is it ok to accuse people of being government agents, shills, spies, or astroturfing, just because they have a different view on some geopolitical or economic question? Obviously we need to not go there.
It's fine if you're not persuaded—I don't expect that—but please consider the downside of being wrong. What if this person is as innocent as you are, motivated by the same things as you? Can you imagine what it would be like to show up here and see it debated whether you're a spy and a liar? Even a single case of someone being unfairly subjected to that is unacceptable. If the community is to avoid "sinking its teeth into itself without realizing it" (Schopenhauer's memorable phrase) and falling into a poisonous swamp, we need a presumption of innocence. And so we do: the guidelines say Assume good faith. If you stand on the dry ground of that assumption, I see no path that gets you to that user being a bad-faith actor any more than you or I are.
I feel bad about holding up an individual user to some sort of public trial like this (another reason why the guidelines ask people to email concerns to us rather than posting them here)—can you imagine what that must feel like? But since the issue is the integrity of the community and its moderation I feel like I'd better say something.