Jethro wasn't disregarding the bigger picture and stirring up internal strife at a crucial moment; rather, if he didn't eliminate Ferdinand now, he'd never have another chance.
If he were truly devoted to the public good, Jethro should have wholeheartedly assisted Corkdor and Ferdinand, but how many people in this world are without self-interest? Jethro came to Ukraine with injuries unhealed, not to share the worries of his boss Deyo but to seek greater benefits for himself.
Unfortunately, Deyo was incredibly unreliable in the way he handled things. Since he had summoned Jethro and promised him control of the overall situation, he should not have sent Ferdinand, and even more so, he should not have sent Corkdor after Ferdinand.
