As with any idea, people come to believe and subscribe to ideologies because they are genuinely pursuasive and they are persuasive because they contain substantial - and often meaningful/relevant - truths (if biased and omitting other relevant truths).
However, censorship is exactly the wrong thing to do.
If these pockets of knowledge are cordoned off, and inaccessible to causal observers then fewer people will know about them. There will be less people who are well versed in the ideas, and as a result fewer who are able to identify and explain their limits and context. This makes it far easier to radicalize folks.
It's also super intuitive, of course censorship increases radicalization. That's why a corrupt government censors, to have better control of and more precisely manipulate their beliefs. Something that wouldn't be possible if everyone had more information.
So yeah, I disagree.