This is why permissionless protocols for social media are needed: https://reddit.com/r/worldnews/comments/10x1fif/turkey_blocks_twitter_after_public_criticism_of/

Chasing Curiosity. Empathetic Accelerationist. Founding Fullstack Engineer @icebreaker. YC S16, KB7. 
icbk.me/tayyab.fc

I’m not the most savvy, but would they be able to block it on an ISP level? If for instance your cast was decentralized, couldn’t you access from pretty much any domain name that supported the protocol?

Agreed on your premise. But Turkey could still block applications built on a permissionless protocol. 

Leverage is still there.