Shen: King of Digimon
Previously Shen: King of the Mist
Cause he is more powerful. That has nothing to do with strategy.
And Kimimaro was trying to kill everyone during that battle. He didn't have that reservation Haku did because deep down Haku was a good person who didn't want to fight to the death. Kimimaro was not that, he was misguided and a loyal solider to Orochimaru through and through. But he makes casual remarks about threatening to kill Tayuya for her "failure" so he is not like Haku in that regard.
He is however reserved, honorable, and respectful. Such as when he paused his attack for lee to take his medications. Sounds pretty honorable not to attack someon when they are weak XD.
Given haku was a bit more pure and kimi a bit hardened, they have a similar principle. Even in reference books it said that Kimimaru had all four of the best traits of the sound’s 4: Jirobo’s strength, Kido’s tactics, Sakon’s durability, and tayuya’s Wrath.