I really disagree. Some of these groups barely existed 5-10 years ago and now they are everywhere. Violence cases like the one in the story is going to make them lose a lot of credit with the public, but if the other side escalates as well (see antifa[0]) things may get even worse.
I wish we could all accept our differences more civically, but I don't know how we can make that happen.
[0] I fully expect antifa to get stronger after this.
I don't like this, but violence is a proven remedy against fascism, possibly the best one. Engaging them in good faith debate in the marketplace of ideas isn't.
Are you familiar the second world war? I'm Italian, the town I'm from was a few hundred meters away from the gothic line. It was heavily bombed by the allies, the retiring nazis and local fascists blew up the bridges and rounded up people for labor camps, the hills around are marked by the graves of partisans. It's possible to stop this sort of thing earlier, with less violence, ideally only state sanctioned violence (since these people tend to commit crimes, as seen in this case).
You think that there are equivalent sides to the argument? I'm going to quote Sartre on antisemites:
“Never believe that anti-Semites are completely unaware of the absurdity of their replies. They know that their remarks are frivolous, open to challenge. But they are amusing themselves, for it is their adversary who is obliged to use words responsibly, since he believes in words. The anti-Semites have the right to play. They even like to play with discourse for, by giving ridiculous reasons, they discredit the seriousness of their interlocutors. They delight in acting in bad faith, since they seek not to persuade by sound argument but to intimidate and disconcert. If you press them too closely, they will abruptly fall silent, loftily indicating by some phrase that the time for argument is past.”
I think the kind of rationalizing you're doing is not much different from the rationalizing people on the other side of the political spectrum do. I had similar discussions with people from the other side and they argued similarly to you. I think your quote is broadly applicable to both sides as well.
(keep in mind that every time that they have to move, their numbers are diminished along the way)