Not promoting the video in their algorithm would basically accomplish the same functional difference as censorship. Ditto for any platforms that can demote content from their ranking.

Like I said, I [mostly] agree. However, there's precedence that publishers be free to pick and choose the content that they publish. Even if it isn't fair, this is a concept that's already existed at various scales for hundreds of years. To single out YouTube for censorship-by-curation would be much more difficult than to guard against them for blatant abuses.

I'll give you an analogy. In America, businesses can't pick and choose people on the basis of their skin color or their sex. Obviously, discrimination in hiring still exists to some degree, but because it's covert or the result of implicit biases, there's a limited number of things you can do to address that discrimination. On the other hand, if the PR for a fast food chain goes on TV and says that the company only hires white people, that's unambiguous and has no conflict with the rights of the corporation.