Nah I'm really starting to see through this whole "neo-Nazis are an oppressed minority" thing... the thing is, their targets usually have no control over what they are (black, gay, disabled, whatever) but you definitely choose to be a neo-Nazi. You're not just born hating people.
I offer an alternative theory: that forcing companies to accept them on their platform gives them a feeling of legitimacy, emboldening them, making others feel more welcome to join them and increasing the problem. Whilst stamping them out at every turn sends a message that their hatred (and the attempted genocide it's been shown in fairly recent history to escalate to) is not welcome anywhere in modern society.
Deep down I think most people want to be accepted. Not making them feel accepted, instead getting a door shut in their face everywhere they go, might cause some to think "gee why does no one want to associate with me" and re-evaluate their positions.