Sakaki's gambit would have been a good and clever display of part of what Katsujinken actually stands for...if Matsuena wasn't so hell-bent on depicting the heroes of (his brand of) Katsujinken as sissies in general. Sure, the endpoint of Katsujinken is the creation and protection of peace--and does emphasize having the ability to resolve conflicts without resorting to bloodshed...
...but those who came up with the philosophy (it is real, after all) weren't so naïve as to think that that will always be the case. In the end, if you fight--even unarmed--you're taking your life into your own hands: if you're trying to win a physical fight--the way Kenichi himself does, when he remembers to stop being a punching bag--there's always the chance that one of your blows can seriously harm or even kill your opponent; the reverse also holds true (which Matsuena saves Kenichi from frequently).
It's not as if every conflict has to be resolved with killing, but Matsuena's making his heroes--especially Kenichi, who is the most pathetic about it--so squeamish about it just ruins their appeal. Those who do evil definitely aren't so squeamish, and it's not a simple spanking that will send them away: Matsuena pretending that this isn't the case is why that major problem in Silkwat Jenazad could only logically be resolved, in the end, by another Satsujinken practitioner.
Hongou dealt Jenazad a killing blow to conclude the fight, and Jenazad was still going to take Hongou with him, having died standing after that--and Matsuena still meant to tell the reader that going for a nonlethal win against something like that could work?