Does it really matter if an outside group comes to town to help the people of that town protest the monuments?
To me it does. It creates sense of false consensus and it does impose outside influence on the locale. I see ANTIFA protests as mostly intimidation tactic and show of power from the radical left. Tearing down of statues is a display of muscle and a message - "Look, we can come into your community, do whatever we want lawlessly and get away with it. You better fall in line."
Think of it this way, how would you react if a bunch of Californians chose your neighborhood to protest Trump because your neighborhood voted for him? Along with property destruction and masked thugs intimidating local newspaper reporter? The same arguments - it is anti-racism, for promotion of equality and so on can be made.