You have an implicit model of how radicalization works which is out of sync with the model others are applying.

The counterexample is that, when racist/fascist/white supremacist content became easier to access through online unmoderated forums such as 4chan, the level of online & offline activity and recruitment became higher.

Secondly, it's hardly news to these communities that they are disliked by others. Have you met an Edgelord?

CloudFlare is under no obligation to serve 8chan. There is nothing radical about denying service to unprotected classes of people you don't want in or using your business.

I would agree this is a problem if the US Government was trying to suppress speech.

They're not being banned or silenced. They're being told "get off my property".