> why it is that Scott Alexander feels like he's in danger
I think Scott's fear (rightly or wrongly) isn't that his own opinions will be his downfall, but that those politically on his own side will attack him for providing a platform to the enemy. I think he sees himself in the same position as Steve Hsu, who was just forced out of his position at Michigan State despite Scott's attempt at public support. The were various criticisms of Hsu, but the main ones seemed to be that he provided a platform for people with unacceptable opinions (Stefan Molyneaux, Ron Unz). I don't think these two are active on SSC, but given anonymous handles, they might turn out to be. Others with bad reputations (Steve Sailer comes to mind) post there civilly, and are treated with respect. I think indisputably there exist some people who consider this to be grounds for "cancellation".
> What form does this supposed cancellation take?
The same as pushed out Steve Hsu: public pressure by a small number of people against his employer for his promotion/tolerance/association with someone who holds less socially acceptable opinions than he does. Scott's view (and mine) is that it's better to have open discussion of unpopular opinions so that they can either be refuted or become accepted. Others think that the ideas are too dangerous to be discussed, and discussion needs to be prevented lest they become more widespread. Some of those who hold this second belief have shown themselves to be effective at pressuring employers to fire those who they choose as their targets.
> one thing we can't really debate at this point is whether Scott Alexander is "out"
I think you are viewing things with more of a binary computer security point-of-view than is appropriate: in normal life obscurity does make a difference. Making up numbers, at this point, 99.99% of the world has never heard of Scott by either his real name or his pen name. Of the remaining .01%, 1 out of 100 know him only by his real name as a local psychiatrist, 98 out of 100 know him by only by his pen name as a blogger, and 1 knows and associates both identities. A prominent NYT article might double the number of people who associate his identities, and he thinks this might double his risk of having professional problems. Is he wrong? Maybe, but I can see why he has the fear even if he thinks his beliefs and approach are overall good for the world.
> You can think it's good while I think it's very bad.
I think this thread has run its course, but perhaps in some future one (if it comes up) you could explain what you think made SSC "very bad". Like HN, I feel it had problems as a community, but was overall a good thing: it enabled better direct communication between people who otherwise communicate only through garbled media proxies. Is this the problem itself, or do you agree that this is a a positive but think it is outweighed by something larger?