The slope is not nearly as slippery as you're imagining it to be. I'm not sure
literal white supremecists are the shining beacon upon which you want to hang your argument (if I'm wrong on this, you don't need to read any further). We're not talking about a controversial political opinion, we're not talking about coastal liberals shutting down good American conservative free speech, we're talking about
white supremecists who refer to themselves as
genocidal. People who want to murder (and have done so) non-white people just for the crime of having a different skin color.
But beyond that absolutely ridiculous argument, yes. The Internet is free-as-in-freedom as long as you have an IP address. If you want to start your own competitor to the World Wide Web because a few private companies exercise their right to not to business with you, you can do that. The Web and the Internet work without domain names, and if you really need your message out there and your followers really need to hear it, is typing in an IP address too much work? If it is, then your message might not be as convincing as you think it is. But even still, you can host your own website or Internet service regardless. And you can start your own registrar and host your own servers and make your own payment processor. That is entirely possible and at that point only the government can stop you (and even then, you can choose your own government like The Pirate Bay did). If your movement is stopped by a lack of convenience, that's not Facebook's problem.
Saying "but Facebook banned me" as if Facebook was the entire Internet or even the entire Web doesn't fly. Only you can give them that power, and you can take that power from them whenever you want to. Being banned from Twitter/Facebook/YouTube is only a problem if you honestly believe that Twitter/Facebook/YouTube owns the entire Internet. But they don't. You're free to start a competitor any time you want.