I’d probably describe myself as a free speech absolutist as far as the government’s concerned, but my personal opinions about free speech have little impact on 1) how white nationalists use arguments about free speech to mask their ideology and 2) how anti-fascists choose to react to white nationalists.
I think Boston showed exactly what you said above; overwhelming numbers of peaceful protesters coming out to condemn white nationalism is a huge disincentive for white nationalists to organize. Likely why they cancelled their “America First” rallies. That kind of mass peaceful allyship is also what many of the anti-fascists who are willing to fight say they want from progressives and liberals.
My overall point is that when we get hung up on our ideals around free speech, we can miss the ideological stakes as well as the tactical choices advocates are making — that’s where the real politics is happening, at least in my view.