General Specific is either a dumb supervillain, or out for revenge on Sheep.Why that specific sheep?
The world is full of sheep, but that specific sheep did something to the General.Hence the pursuit of that sheep when another would do just fine.
Sheep is the last of his kind.General Specific just had a sheep-powered ray gun made to commit two evils at once.
General Specific is Obfuscating Stupidity and knows full-well how stupid his actions are.He's just doing it and pretending to be incompetent to get the Angry Scientist and Private Public to do his dirty work while he siphons government funding. If he acted as smart as he is, then he wouldn't get much face time in the show.
General Specific is cursed by his name to go after the specific sheep.That's all. Doesn't he act similarly in other plot points?
The Angry Scientist prefers to be called by that because his father was a mad scientist got stuck in a cuckoo's nest
Following "Agony of De-Bleat", the antagonists intentionally fail to capture Sheep.The episode ends with everyone being fired, if not for the interference of the Angry Scientist, Plot Device, and Private Public. Following this episode, it's very possible that any plan that would succeed again is quietly sabotaged. "Daddy Shearest" has this happen blatantly.