again: i usually side with the aclu.
i'm a really strict ideological liberal on speech - but that actually doesn't imply a lack of oversight. ideological liberals should be holding to the harm principle, which was outlined by mill. and, i think there are good reasons to argue that some types of speech are harmful.
it's very careful, very delicate.
if an old man wants to walk down the street by himself and wave a flag as he holds to some delusional and scientifically debunked concept of race supremacy, is he actually harming anybody? probably not. but, if a militia wants to march down the street with guns and chant racist slogans, there's some serious harm being created, there.
what the aclu usually represents is something closer to the first scenario, and i'm usually going to side with them on it. the situation in virginia is getting dangerously close to the second situation. and, the organization should consequently ensure it's being properly judicious about what it's doing.
should this have been shut down ahead of time? it's a judgement call. but, some of what i've seen from these protests does get very close to incitement, and if that evidence did not exist before, it does now: there's a reason to shut future protests by this group down on the harm principle. and, there's perhaps a reason to charge some individuals with incitement, as well.
https://www.vox.com/policy-and-politics/2017/8/12/16138326/aclu-charlottesville-protests-racism