Short of flawed game-design, where character choices are made for you (trust me, I have issues with this one), then it is easy to just say "my character is not affiliated with these actions, and only assists with x or y while I go through the motions". I do it with my own druid, demon hunter and hunter. I think it's really boring and tired to keep the whole faction war going over stupid excuses, so to me, I am going through the story as it's presented to me, while the character is just serving as my vessel, but would otherwise not do it.
That doesn't relate all that much to how druidism fits into one faction or the other.
Depending on your values, exemplified in Pathfinder, there are some nasty druid archetypes that you wouldn't normally associate when you say druid. Like a druid that specialized in poisons, literally able to sweat it, while another druid specializes in decay, rot and vermin. All part of nature. Like burning down a field, or laying it barren for a while helps grow new crops later. Cycle of life. Birth, life, death, cycle continues. You can go off it in a generalized sense, or specialize.