You seem strongly opinionated on this one though, I'm curious, what do you think of Tor or BitTorrent? Should such services be banned as they aid in the distribution of this type of thing too? If you're running a Tor middle node you're part of the distribution of not just all sorts of propaganda like this, but far, far worse things.
Do you think banning these services, reigning in control of information to "help prevent radicalization" in a China-esque way would be a good decision? In my view this is just part of living in a free society, freedom sometimes costs security.