Some defend them by saying they are protesting against fascism, white supremacy and nationalism, but they do more than that they also falsely accuse people of being those things because their politics are to the right. They even accuse people of those things just for carrying the American flag. They sometimes even attack people without a shred of evidence of those things.
I suspect that they do not really give a damn about those they claim to defend and are just a bunch of vicious thugs who enjoy causing trouble.