The clue is in the headline:

Steemit Censoring Users on Immutable Social Media Blockchain’s Front-End

Short version: Steemit, a blogging/social media site operating on the Steem blockchain, banned an account associated with a person or group called The Dark Overlord, which claims to have possession of — and, if a ransom is not paid, plans to release — insurance files related to the 9/11 attacks.
Now, as someone who publishes on Steemit, I’m not especially happy about Steemit’s decision to block users. Any users. For any reason.
But take a second look at that headline. See the words “immutable social media blockchain?”
Steemit is not Steem. Steem is not the Steem blockchain.
Steemit is just one of many (“more than 324”) apps/front ends that people can use to publish stuff to, and read stuff on, the Steem blockchain.
Just as an example, here’s the prettified Steemit version of an article I published earlier today, and here’s the same article, not so prettified, as stored on the blockchain.
You need some kind of tool to publish to the Steem blockchain. And you need some kind of tool to read stuff on the Steem blockchain. Steemit is the easiest and most convenient way I’ve found to do both. I’m not sure I’d bother with Steem if not for Steemit. But there are other ways.
Not only can Steemit not stop The Dark Overlord from saying anything he, she, or they want to say, Steemit can’t even stop he/she/them from saying it with Steem.

Imported from the original KN@PPSTER