Notes on free speech and legality
Obviously, whether to allow hate speech on a hosting platform run by a corporation is different from whether to allow someone to speechify in the town square. (And obviously, explicitly expressed speech like the Daily Stormer or Stormfront is different from baking a cake. Implying equality between the two is rather simple-minded.)
But in the USA, even the right to free speech in public forums is not unlimited.
"Fighting words" and lewd or obscene speech are not protected. The Sedition Act made it illegal to make false, critical statements about the government, and the Smith Act made it illegal to advocate the overthrow of the government.
Notably, one of the most-quoted standards of US political philosophy is the concept that "all men are created equal." (Yes, in the time of founding dads, that ideal was very far from realized. But it is implicit in nearly all matters of citizen rights in the US.) The foundational philosophy of Nazism and white supremacy, on the other hand, is that all men are not created equal: pinky-beige people are supposedly better than brown ones. Books like "The Turner Diaries", a revered narrative among white supremacists, are fictionalized accounts of governmental overthrow by said whitey-tighties.
The point being, there are legal limits to speech in the US, and in its rhetoric white supremacy treads close to the line of a couple of them: false criticism of the government ("Government is run by a Jewish cabal!") and advocating overthrow of the government ("Must replace corrupt US government with proper Nazi system!")
Personally, I think Jeftovic's rationale was pragmatic and sensible: Hosting this group's site would have created a troublesome situation for his company, and probably would have impacted their profits when other groups began avoiding our platform. To my knowledge, services are not legally required to host hate-speech or pornography, or solicitations for illegal acts such as murder-for-hire or human trafficking. He's within the pale.
On the lighter side -- go ahead, punch a Nazi. Your gran would have done.