STEEM blockchain is censorproof. Steemit is an application on top of STEEM blockchain. Posts that show in steemit can be flagged down so it's hard to see them but those posts can still be seen in STEEM blockchain.

If post in steemit is removed, it can still be found in STEEM blockchain. You can see the blockchain from this link https://steemd.com/

This post's url is https://steemit.com/steemit/@freedomrings/is-steemit-censorproof
if you change steemit.com to steemd.com you can see this post in blockchain
https://steemd.com/steemit/@freedomrings/is-steemit-censorproof