Yaghmour: gitgeist: a git-based social network proof of concept

That sounds the same as removing any other kind of illegal material - copyrighted works, illegal porn, etc. That's an issue with blockchains: https://blockchain.comsys.rwth-aachen.de/, https://www.bbc.co.uk/news/technology-47130268, etc. Immutable history is a nice idea until you're legally or morally required to mutate it.

But from the description of gitgeist, I don't see why that'd be a problem for it. It sounds like every user has their own independent git repository, they refer to other users by repository URL, and posts are represented by directories and files. None of it intentionally depends on commit hashes, so rewriting history should be fine: you can delete stuff from your own repository and continue participating in the network as normal, and if someone else has a cached copy of your now-deleted commits then that's not your problem. It doesn't seem to be depending on any unique properties of git, it's just using git as a database and as a data synchronisation protocol, so it's basically the same as if you used any other kind of database.