This isn't censorship
They aren't preventing Daily Stormer from being heard, they are refusing to provide them a platform to shout from. You may support free speech, maybe to the point where if you owned a vacant lot next to your house you'd be happy to make it available for public gatherings and allow republicans, democrats, save the whales, cut our taxes and so forth to use it to get their message out.
Perhaps you may draw the line at pro choice and pro life gatherings, not because you want to censor them but because emotions get inflamed to the point that when some people find out you are responsible with giving the "enemy" a platform to spread their views that they decide to respond by vandalizing the car sitting in your driveway next door. Sure that's illegal, but it is still a hassle having to drive around a car with "baby killer" spray painted on it, and your insurance going up when it happens twice in six months.
Even if you publicly say you are 100% against Daily Stormer's speech, if you give them a platform you are going to have deal with a lot of negative publicity/boycotts, and likely be subject to constant DOS attacks that affect your other customers, etc. Even nazis have a right to free speech, but companies are not required to provide them the platform, and it isn't a violation of their free speech for others to say "if you give you them a platform, I will boycott you". It is no different than if company X donated money to Planned Parenthood and you were pro-life, you deciding not to buy company X's products.