No, the b slap would not have killed the man. But the beat down we are used to seeing in these situations could have. How far do you think that situation was from becoming a serious beat down of that guy? One guy pulls a shiv and its over.
Note to self: If ever meeting GOFIGURETITANS in a park for a brawl, he carries a weapon and is on the lookout for shivs. Do not bring sharpened toothbrush or Desert Eagle. Bring Tank.