@joyRThe Darjee are described as having an avian physiology, they are also described as having developed a fusion drive. Apparently humans are absolutely incapable of reverse engineering alien tech that they are familiar with, yet a budgie built a fusion drive...
Could someone make up their mind without attempting to have it both ways?
It ends up being both ways because the Darjee changed the scenario.
Scenario 1) The Confederacy does nothing. Earth is invaded by the Swarm, no help is given, and Earth
eventually fights off the invasion, but may not have a viable planet/ecosystem left.
This does nothing for the confederacy, as Earth is only one point along the corridor that the Swarm was invading along. So humans might survive, but nothing else "in their neighborhood" would, because nobody else is able to fight the swarm off, or slow them down.
Scenario 2) The Darjee make contact, and get humanity involved in blunting
the entire Swarm invasion. (Which is the scenario now underway)
This diverts resources away from Earth that otherwise would have been available for Earth's defense. Of course, it also means the Confederacy can provide resources the Humans wouldn't have had otherwise. And my earlier comment was kind of incomplete.
The Confederacy knows that earth is "a lost cause" in regards to being able to save the planet from widespread devastation. They have no scenario where anything on its surface survives in any meaningful form. The number of survivors is likely to number in tens of millions at best.
"Throwing more resources at it" doesn't appreciably change the outcome
for Earth,
but could significantly impact the outcome for the rest of the spiral arm. So Earth is a "lost cause"
because it starts at a point of diminishing returns from the perspective of the Confederation.