Ancient history and accusations of arrogance do not concern me. What concerns me is the immediate threat the black dragonflight poses to us and everything left in this world that we hold dear. If they continue to increase their numbers, and they WILL, they will grow restless, they will LEAVE the Burning Steppes and they will descend on the neighboring lands, incinerating everything in their path. You may vouch for letting them be, but I for one do not intend to let a threat like that run rampant. Blackwing may indeed be the source of the corruption, but as it is, he is out of our hands. I say we strike where we are able to make a difference. And that is at his children.
Yes, I would also rather that we might entice them to pull back and make peace with us by offering them cupcakes and sugary tea. But that is not the way things are. This will end in blood and grief, one way or the other.