The ritual that will seal the grove into being permanently surrounded by goblins, gnolls and other Absolute forces - about which Druids dont care and dont want to know anything. Because they are biggoted close minded exclusionists - and racists! TLM! TLM!
This. The writing sets the tieflings up as paragons of virtue to beat you over the head with a message nobody was going to question anyway. They cannot make the tieflings more "evil" or that message is muddied, but they also cannot do anything about the druids' perspective because the ritual is not going to do anything for them. How is some bramble going to protect them from fire?