However, the IPFS team is aware of this problem, and is building in measures to allow nodes to opt out of storing globally available blacklists of known bad objects (i.e. pirated content or illegal content)
In practice, this is definitely a really hard problem to solve, and very important. But I think doable.
I'm personally glad that the fathers of the internet had better things to do than moralizing legality.
Sounds like the opposite of something most would consider "important".
I think blocking a hash can already be a victory, since it basically makes all the metadata that was associated with the hash useless and forces reseeding under a new hash and publicizing that hash. As long as you make it inconvenient enough, very few people will bother, which is the best the copyright holders can hope for.
Reseeding might be pretty easy though in IPFS since there is a block layer below the object layer, and I guess you can't really block block-hashes.