I thought it was a good allegory to how veterans are treated once they return from war. As someone who volunteers time to help make sure vets get proper treatment upon returning home, I know well the impact it can have for them to feel appreciated. These guys go through a lot and then to come home and be ignored and neglected can be devastating.
So put yourself in Edison's shoes. You fought for your planet, lost countless friends and fellow soldiers along the way. You were victorious, and upon returning, the people you fought for have no use for you anymore but need to give you *something* to do, so they throw you a bone in the form of an old cargo ship and tell you to go make nice with the very people you were just fighting.
Now imagine you're on this mission and along the way you find yourself stranded on an alien world, your calls for help going unanswered. Thanks, Starfleet...you send us so far out that you can't even rescue us if shit goes south. Like any good captain, you do what you can to keep your crew alive, but in the end only 3 of your survive.
So he uses the alien tech to prolong their lives with the unfortunate side effect of it obviously transforming them into whatever alien race left the stuff behind...which also can't be good for the ol' psyche. Pretty clear as to why he's be pissed off at the Federation to me. A little extra time could have been spent on fleshing him out and really pressing the "neglected and forgotten" angle. I would bet that a fair amount of deleted scenes on the DVD will reveal more about him.
I also didn't see the Abornath (sp?) as a superweapon, as it seems like a fairly straightforward biological weapon. I also liked that (finally) the bad guy ship wasn't some gigantic black dreadnaught (Vengeance, Narada, Scimitar, Borg cube) and was dangerous *because* they were small and maneuverable and not simply because they were bigger and badder than the Enterprise.