![Smiley](https://bitcointalk.org/Smileys/default/smiley.gif)
I almost cannot see any downside with this : It's definitely better than the current way of investigation... For someone to dispute the claim, they'd have to say that the person pretty much held him to hostage and took the content and then hashed and "registered the existence"...
Coming to think of it, why a blockchain? Why not just a distributed database of hashes that is verified? The blockchain per se may not be necessary right?