So what? If someone scrapes the net and steals artwork, then posts it on your blockchain, that should be "irrefutable proof"?
You guys are megalomaniac pretenders.
I belong to a organisation that protects artists rights and has lawyers on call all over the world, plus I have a watchdog service that alerts me to any one of my images on the net.
I have no problem with people sharing my work, but if they earn coins for it, that makes it commercial. And those I have my legal service send take-down notices. Now if those notices cannot be followed (since you say "unalterable") then your entire blockchain is in violation of the law!
But Steemit can comply with a take-down, since one can edit posts.