Hive is a decentralized public forum. And the "costs" for supporting it are spread across multiple organizations: 1) witnesses nodes who operate blockchain software, 2) api nodes that run blockchain software + other software that requires more hardware resources, and 3) front end website operators (peak.com, ecency, hive.blog, actifit, etc, etc).

It is relatively difficult for witnesses to censor blockchain information (it requires 75% of the witnesses to agree to the censorship). On steem, before the takeover, this happened only once, when witnesses censored transactions from the steemit account to prevent it from taking over the chain.

After the takeover, however, censorship became quite easy there, because two entities (steemit+some Korean organization) gained enough combined stake to control the entire set of witnesses. After this, massive censorship resulted. So this is the primary censorship weakness of Hive: if someone gains enough stake to control all witnesses. But even in this case, as happened with Steem->Hive, the code can be forked to avoid the censorship.

There are fewer API nodes than witnesses (maybe around 10 nodes), and API nodes can also censor, but this form of censorship is even more limited than what is possible by witnesses, because it only takes one API node that is refusing to censor information in order for the information to be easily available to all Hive users.

Also, we've dramatically lowered the costs of running an API server nowadays, and there is no election requirement to run an API node, so any information freedom advocate can decide to run a Hive API node if they see censorship at this level.

Similar logic applies to the frontends: it's basically the same situation as for API nodes (and most frontends also run their own API node).

From my point of view, the above are the only points available for actual censorship of information on Hive.

However, there is a related issue, which I believe is the one you're concerned about: "downvoting".

Downvoting does not actively prevent information from being read. You can still read any post, no matter how much it is downvoted, on every Hive frontend. On some frontends like hive.blog, you may have to go thru an extra step of clicking on a button that says you want to read it (but on ecency for example, there is no such need). The "hiding" isn't a blockchain level thing, it's just an optional thing done by the frontend software. But to my knowledge, there is no Hive frontend that doesn't leave you with an easy option for still reading the post in such cases.

But Hive is more than just a public forum. It also has an "incentive" system to encourage information sources to post information on Hive. And downvoting will potentially dis-incentivize some posters from posting, especially if they are primarily posting for the reward and not just because they have some reason to share the information. So, for information sources where the reward is a primary motivator, voting both positive and negative can affect what information gets shared. But I don't consider this censorship. This would result in some censorship if we lived in a world where people's primary income source was income from posting articles on Hive, but I don't think we live in that world.

To get down to specific cases, I don't think that whoever is posting RT articles (I don't really know if it is RT or not) is particularly motivated by the rewards, and so they keep posting despite the downvotes. If they stop, I think it will just be because they don't think it is worth their time, not because of getting posting rewards or not.

Now, there is one argument still left that could be related to downvoting as a form of censorship. Another way to view Hive is as many "public forums". In this view, every community is a public forum, trending is a public forum, hot is a public forum, and everyone's "feed" is yet another public forum (this is a really cool feature is it means literally anyone can easily establish their own public forum).

Downvoting a post lowers posts in the rankings of many of these forums (it doesn't affect feeds, however). So a downvoted post is not likely to be read in the trending forum.

But I view the trending forum as an "overbooked" public forum. There's not enough " attention time" to allow every "speaker"/poster to have his equal say on the trending forum. So somehow such speakers have to be prioritized. This is an unavoidable problem: it is a hard limitation on human attention.

Upvoting/downvoting is the mechanism that Hive uses to make this determination. Not everyone gets the chance to "speak" on the trending forum whenever they want, and unpopular posters may never do so, but Hive still supplies plenty of other public forums for those posters, and it isn't difficult for people who want to listen to them to find them.