> Those aren't even slightly equivalent positions, though. One is a request that material dealing with shocking or upsetting subjects be marked as such so that people who may be affected can avoid it, and the other is unsubstantiated racism that has been known as wrong for a century or more.Technically speaking they're categorically equivalent in that they're both sanctionable under freedom of speech. From that perspective, whether or not you find one or the other more sanctionable has more to do with your personal opinions than it has to do with accuracy.
Since Twitter is a private organization it can freely decide to curtail freedom of speech on its platform, because that right is not guaranteed (or rather, relevant) in the private sphere. But that puts it into an uncomfortable position because it must then start being opinionated itself. Which opinions are the "right" ones? Which curtails are merely reducing spam and abuse, and which ones are censoring honest but unpopular opinions?
Now that aside, I agree with you that there is a difference between broadcasting unpopular opinions and targeting unpopular opinions towards another person. This makes the situation more difficult for Twitter, but there's a credible argument that curtailing the expression of those opinions in either context is censorship, while curtailing the expression of those opinions in the targeted context is spam and abuse reduction.
Twitter is fully allowed to engage in censorship, but it's probably strictly more beneficial from an inclusionary standpoint to invest in sophisticated tools for empowering users to reduce the spam and abuse targeting them (or which they come across) than it is to invest in sophisticated tools for curtailing "wrong opinions" across the entire platform. Most people can agree on the most extreme opinions that should be censored (though obviously not everyone). But it's hard to make companies the arbiter of which other opinions to get rid of, because from the obvious extreme ones there is a long, long tail of benign opinions that many people will reasonably (and unreasonably) take offense to.
For what it's worth, I think the situation is extremely complex and companies like Twitter are (somewhat unfairly) demonized for not doing enough, or doing too much to reduce the problem. But I don't think there's a substantially easier or more straightforward way of navigating these waters than Twitter has done, given the same capability and information.