Ah, Earl...
NBC said "We're going to cancel it." Then Garcia said "Fine! I'll wrap it up!" Then NBC says,"NAW, we're gonna wait and see about that. Do that cliff hanger ending you wanted." "Fine," Says Garcia. Then NBC says "You know what? it's too late, but we're completely screwing around the network, so we're ending the show as far as you got."
And that's why we have a cliffhanger. NOT because Garcia wasn't going to wrap things up anyway, but because NBC is run by idiots... this was during the infamous Jay Leno 10 PM show debacle.