I think that only text is stored on the Steem block chain. As I understand it, the images are stored on AWS cloud servers, so they can be taken down. Steem's main areas of concern are probably copyright violations and doxing. (It is possible to encode binary images in text, but post size limits probably constrain the harm from that vector)

I think sites that use chains like IPFS or LBRY for hosting binary files (such as DTube) have more of a concern with things like child and non-consensual porn or other undesirable graphical content.

I wrote about this in Block chain is fundamentally and irreversibly changing intellectual property and online privacy. It's a consequence of immutability, and I think the same issue applies on pretty-much all block chains to some degree or other.