Why did McGinty favor McMurdo?

McMurdo is a master manipulator... he is so good at his job that even McGinty, the leader of the Scrowrers, is taken in by his deceptions. When McMurdo reveals his criminal history (false history) and stands tall even when a gun is pointed at him, McGinty is drawn in. Mcmurdo's professional demeanor accelerates not only his acceptance by the Scrowrers, but his acceptance as a loyal and trustworthy man by McGinty.