That is a huge overinterpretation.
Riboku making a plan to keep Shin at bay doesn't mean he thinks Shibashou would loose to Shin. It's just that Shibashou has a job to do - to kill Ousen. And Riboku can't have anyone intervene, so he sent HSU on a wild goose chase while Shibashou can focus on Ousen without worrying about special units. Riboku simply believes this sort of placement would make the best result.
Ri Boku cited Shin’s martial ability and slaying of Hou Ken as reasons why he decided on his strategy, and stated he would have thrown the entire army at him if he were the enemy’s Supreme Commander.
I didn’t say he
believes SBS
would lose. Just that he doesn’t have the confidence to strategise under the assumption he would win, thereby making it too risky.
RBK witnessed a starved and injured Shin with 15 days of brutal fighting behind him defeat Hou Ken. Why wouldn’t he believe SBS could share his fate under much more level circumstances? If he couldn’t afford to lose Ba Nan Ji in the last battle, he certainly can’t afford to lose SBS in this one, so why take the risk?
I wouldn’t categorise RBK putting his own life at stake in a close chase as a wild goose chase either. A wild goose chase is chasing something unattainable. Thats not what happened. RBK assumed absurdly high risk and was injured in the chase. He put his own life on the line to ensure his year of preparation wasn’t wasted, and he did it because he believed it was necessary to enable Seika’s commitment to the best of his ability.