[quote=thewizardguy]
Bob could, but he's bound by his peculiar code of honor. He never breaks the rules of a game, not unless his opponent does so first. Unicron, being a duck, is incapable of breaking the rules and living.
[/quote]
Bob cannot kill Unicron, no one can. Not even Primus, not even god himself. Unicron is a force of nature, he exists permanently. He can, however, be defeated.