Unfortunately the decentralized nature of steemit will make this a complicated issue. Images and video arent kept on the blockchain but if this guy or others starts posting URLs or other text based means of spreading it then no matter what the admins do it will be up forever.

I dont know what the devs plan to do in this situation but this is why we cant have nice things. If no action can be taken besides flagging and moving on then this can damage the image of steem for eternity.