I thought this plot point was poorly written. Whatever totalitarian system was supposedly in place regarding the Bushido code, the game never establishes. So despite the desperate need to vanquish the Mongols, when Jin jumps the fence and defeats them with stealth his Uncle is so appalled at this victory he decides its a criminal action. I found Lord Shimura's action to be thoroughly unconvincing at this moment. In all honesty it doesn't even matter at that point but his uncle is unpractically dogmatic it ruined the story a bit.