Protecting speech is often in tension with other individual liberties that are supposed to be protected, and the purpose of government is to arbitrate those disputes. I don't think there are any that grant unfettered protection to speech-- a government that permitted advocation of treason, for instance, probably wouldn't last very long.
They can still say whatever they like, and, y'know what? Their fascist readers can even still get to it using their IP address-- at least, they could if they weren't hiding it behind CloudFlare.
This isn't censorship. As far as I know, no one has the "right" to an entry in the public DNS, nor is any registrar required to do business with Nazis. Registrars have the right to free association and speech too.
Tbh, I doubt Google knows they're the Stormers' registrar yet; you can transfer domains automatically.
CloudFlare doesn't provide hosting, it's a reverse proxy. But, if you believe http://www.crimeflare.com/cfs.html, the actual web server sitting behind dailystormer.com is hosted by online.net, of France.
Even if it only serves to waste their time, hassling fascists is still a public service.