Certainly if one were to empty a double stack clip into him, things would have changed a lot. The kevlar still leaves a lot of flesh open, and if he were to fall over from the impact into the chest, there's a lot of soft spots that are bound to be hit with 15 or so rounds. Might not have killed him, but you get the idea.
Regardless, he would at least had been distracted and focused on the CCW shooter and would have given people more time to get out.