For me that is a kind of censorship, HOWEVER, the Steemit.com is a property from Steemit Inc, which could ban anyone that they don't like it, is the right of them. Of couse, I think that is a kind of Facebook censorship, which prohibit the free speech, but if you agree with the terms of use, you cannot say that they don't advise you about that.
That is what I like in the blockchain, you can only banned from front-end, since everything he posted continue to be on chain!