I'm ignorant of general D&D lore but aren't goblins more or less just a bunch of savages? Kind of dumb, tendency for violent solutions not really all that diplomatic. You're definitely railroaded as the story currently is, but goblins don't exactly strike me as ever being much more than pawns for someone else. In which case killing their leadership (Tadpole crew) "saves" them since they'd probably calm down with the massive mobilization against the other locals. The Teiflings, they're straight up refugee stereotype so it'd be hard to see them as anything other than sympathetic.
The idea is that Tieflings are unnatural (extraplanar) and Goblins are natural (from Faerûn). I have to admit that when we start factoring in that druids can talk to animals and most of them are more intelligent than Goblins, things start getting a little confusing. You can have intricate conversation with a bear, but a Goblin is always a stereotypical working class Londoner. The Goblins have also taken up worshiping the Absolute, which upset their natural place under Maglubiyet's control. There is even a Maglubiyet priest held captive in the Goblin camp.
None of the druids act like human beings during this quest. At least, if we assume that Halsin taught them his values. If he somehow ignored the fact that his entire grove is a bunch of xenophobic bigots that just needed a reason to hate, I sure hope they explain that later down the line.