The only problem are people putting a morality value on the consequences instead of on the decisions/motivations of the characters. That's valid for posters and some people at Larian. It's not just about that quest. The companion's alignment threads are full of people arguing X or Y are good because they like pets. Go check the D&D alignment description, none of them says you can't like pets if evil or that good have to like pets.
Stealing isn't evil only when you get caught. It's always bad. Saving people because you wanted to get revenge on someone holding them captive isn't you being a goody-two-shoes. Killing the 3 leaders because Haslin won't help you otherwise and he looks like the best healer option isn't you going out of your way to save the Tieflings and play the hero.
I suspect most people have never seen the Raid/Defend the Grove, as the game set you on the "kill the 3 leaders" path from the start. I'm even surprised that they call the Defend the Grove the good path when you have to betray the trust of both the Tielfings and Minthara to get there. You're character is a selfserving asshole on that path.
Bumping this comment. In my first playthrough I was playing a self-centered, asshole, evil character. I saved the grove because that was the option I thought would benefit me the most (Halsin could heal me and Gut tried to kill me). I wonder how many of those "75% of players stood with the tieflings" were playing evil characters...
I can tell you that I was one of those evil characters. I might be several even if they keep track of playthrough and not profiles.