With regard to stories like this lately, it’s becoming my considered opinion that the best way to handle such groups is to wipe them out, root and branch, the way the Old Testament guys did it.
Now go and smite Amalek, and utterly destroy all that they have, and spare them not; but slay both man and woman, infant and suckling, ox and sheep, camel and ass.
I mean, after all, if you kill every last one of them down to the babes in arms, nobody is going to be left to sue you for violating their civil right to be complete and total assholes. Right?