If you only need to make sure your data is distributed, using another P2P protocol such as IPFS and BitTorrent are better option.
I think the "bitcoin isnt made for this" begins to step into the ethical debate which isn't really my focus, but I also believe that as long as bitcoin allows for such a use case even though it wasn't intended for that it does not matter very much. Ultimately, if it becomes a problem for the bitcoin ecosystem as a whole then it will force a solution to be created or bitcoin will fail. Relying on everyone to abide by some ethical standard isn't a great practice so instead of saying "bitcoin should not be used for this" I think the argument should be focused around "If or when bitcoin is used for this..how do we solve for x?". In a way, relying on everyone to stick to what bitcoin should be used for means you're trusting humans to do behave a certain way which goes entirely against the grain of what bitcoin is about at its fundamental core, which is taking away the need to trust humans to behave a certain way.
IMO the community don't rely on ethics to prevent people from doing something unethical on Bitcoin. In this case, it's because :
1. the cost to store arbitrary data on Bitcoin's blockchain is quite expensive (due to big transaction size)
2. there's no standard to do it (aside from OP_RETURN)
3. small amount of Bitcoin might be lost if you use don't use OP_RETURN
4. currently there's no user-friendly software/service to put arbitrary data on Bitcoin's blockchain.
He wants to encrypt some random data and store it on the blockchain. Why "the blockchain"?
The solution is to encrypt the data with GPG, then upload "the data" on some website.