Thought I'd chime in here - the admiral AI has a serious flaw that makes winning this mission (along with Dire Straits) much easier than it should be. Later in the battle, it has a tendency to keep a bunch of ships at an objective for no real purpose. This has been fixed.
Edit: Just played through the mission (needed to anyway, due to all sorts of balance changes in the game). Got a fairly easy victory, but I'd attribute it more to the high-tech ships just being that much stronger. A nebula right out of the gate for the AI side doesn't help much either - all the heavy hitters couldn't get anywhere in a reasonable time. Btw, the new loadout for the Aurora (the flagship) doesn't include long-range weaponry, so there wasn't any kiting involved. So at this point, I think it's just a question of the mission not living up to the "impossible" label.