The thing about joining the shadow druids is that itentirely makes sense why we wouldn't be able to from a gameplay perspective. Their goals are entirely antithetical to continuing the story. They want to close off and isolate the grove. We don't get any indication that this group wants anything more than that, certainly nothing that would require an outside agent. Joining them would mean staying in the grove and ending the game. Why would they help us? They want to be isolated and our tadpole condition, if they were to learn about it, requires us leaving. Either that or staying and risking that we become mindflayers and potentially kill them all. We also have nothing to offer them. We could help them get rid of the tieflings? They asked to do that already and instead we exposed them in front of a group of other druids they now have to kill to keep themselves secret.
