No, again, police can't arrest you simply for joining a white nationalist group, even if that group is known to be violent. That's not probable cause. Same thing goes for Antifa. And no, I don't support antifa because I'm a proponent of peaceful protests. However, that doesn't mean I think every single antifa member should be arrested even if they haven't commited a crime. There are still antifa members who are nonviolent. By arresting every single member of a political group just because a portion of that group is violent, it means you are an authoritarian who doesn't support the Constitution.