Very nice :) I rather like that for once someone alien defends Earth instead of attacking it.

A few minor proof-reading points:

"This was a room where you were forced to concentrate at the matters at hand."
shouldn't that be "concentrate on the matters at hand"?

"...normal, for lack of a better word" shouldn't have a space before the .

"weapons of mass destructions" doesn't need an "s" on destruction

"all which contained inhabited worlds" all of which sounds better, i think. also, stars don't contain worlds, they are orbited by them.

"You have caused the deaths of billion" does need an s

Is it 5 worlds, or 7? at first you say 5, but the avian says 7.

"Her stare conveyed condensation" do you mean condescension there?

"If this outbreak was to happen on Earth, why not destroy it. Why destroy five star systems instead of one." question marks instead of periods?

"decided to punish billions...to death" sentence, consign, or condemn might be better than punish in this phrase.

"The only hubris I see here is you." is in you, or is yours

Hope those are helpful, and that you don't take them to mean I didn't enjoy the story; I liked it, I just compulsively proofread.