Claiming that tieflings are not hellspawns is false. They are.
Tieflings all have infernal heritage, be it baatezu or tanar'ri, or yugoloth.
They are literal spawns of evil. And yeah, druids who are supposed protectors of nature, are not supposed to be happy about them, the same way they are not supposed to be happy about the encroachment of civilization on their own territory. Personally I think that the portrayal of druids as these very strange hippies who somehow always end up being diplomatic and nice is nonsensical.
But then tieflings being nice and an ethnic group of their very own is also nonsensical, because tieflings were supposed to be rare and often come about as the offsrping of 2 normal humans who have a devil or two up in their bloodlines.
Personally I feel like much of the race-hysteria could be resolved in the game if different races simply couldn't have babies together.