Are the shadow druids a large group? The game gives no indication of that. I assumed that shadow druids were a philosophy rather than an organization that really interacted with each other in any sort of broad, organized way. They didn't strike me as a group who had a meaningful wide hierarchy. Like this group would be pursuing their goals independant of any other group Plus on a meta level, I don't believe for a moment that this whole druid questline will be at all relevant once we leave this nameless starting area anyway. That's why their goal is to close off the grove, so that once the plot point is done, we don't have to worry about it anymore.