Free speech is not completely unfettered. Under Brandenburg v. Ohio, speech that incites imminent lawless action - and that would likely cause such action - can be punished under the law.

In all likelihood this appears to be what is happening with kiwi farms. Of course, the issue is that Cloudflare can’t undertake legal enforcement, but they have a terms of use and so contractually are duly within their rights to end service to kiwifarms.