If HN was the primary place where the wast majority of startups got funding, and HN moderator would delete comments in order to influence the conversation between investors and founders, such moderation would very quickly be seen as an abuse of power. It is one form of moderation that I have never seen on HN.
As it is, HN moderators has a rather limited power and rarely been exercising the little power they have. A way to describe this is that people wielding power do not always commit act of abuse, and all power is not equal. There is no true name policy on HN, no rules against people contacting each other outside of HN, no restrictions against people based on political, religious or other views. I can mention the competing communication platform discord and not get banned for doing so. People can read HN without creating accounts, and HN do not block VPNs or Tor.
As a tool for authoritarians, HN moderation is not an effective one. Possible by design. Their behavior has so far not been to utilize power in order to maintain power. There is not much left if you remove power and abuse from the definition of censorship, and so I would not describe HN moderation as it is now as censorship. Occasionally they do things like automatically reduce article weights based on specific political topics, which is a soft kind of censorship, but from what I have seen they have taken a bit more relaxed attitude and not done that so often any more.
However could not the same be said about the app in the article? What does the app do that they can't do through the browser? If apple has no power in this relationship then the impact of the decision should be zero. It seems however that Apple do have some power or else the Russian government wouldn't have gone after Apple to censor the app.
Censorship is just an other word for power abusing their position to limit the powerless. It is not about forcing people and entities to provide a service, its to prevent people and entities that holds power to abuse that power in order to keep others powerless. If that translated in a specific case to being forced to provide a service, then there is always a second choice. They can open up and give up the thing that gives them power. In the case of apple that would be to provide alternative ways to install software without tricks that keeps apple in power. It is an active choice of Apple to be the door keeper for what the captured users can or can't do with their own devices.