Survival Trains Hard
Whether Kinch himself is a naturally easygoing person or the example Col. Hogan sets just makes it easy (calculatedly so? maybe, maybe not) to slip into this even, grounding demeanor, he's not sure. Where the other three members of the core team are twitchy and hot-tempered (and he loves them for it, too!), staff sergeant and colonel run relatively cool.
Even in the grimmest situations, he can sense himself competing with the colonel - who's gonna fly off the handle last? Winner gets...
Well, who cares what the winner gets? He and Hogan don't have to play those kind of games.