The idea of censoring his manifesto is strange to me. You'd think people would just want to argue the points brought up in his manifesto on their merits and win mindshare that way.
We heard he cites Anders Breivik's manifesto in his own (i haven't read them) so the domino effect of self-radicalization is what concerns them i think. A bit like how we have laws against reporting on suicides cos they determined that suicides statistically increased when they were widely publicized in the past.
Well, a good chunk of the US anti-vax movement seems to be ultra-Orthodox Jews: https://www.nytimes.com/2019/05/14/nyregion/measles-vaccine-... Their religous beliefs don't permit them to have unfettered Internet access because it'd expose them to corrupting ideas (like, say, the idea that vaccines are safe).
And yet more than a good chunk of the anti-vax movement worldwide has unfettered Internet access. Ultra-orthodox Jews certainly aren't a factor here in New Zealand.