Of this, I would not be so very sure. What we don't know about the 'mob' in this case is if they would return fire instead. CCW in the face of a violent direct threat...yep, check. CCW in the face of a lone shooter...yep, check. CCW in the face of being cornered by a mob myself...yep, check.
I think the first time they run into a CCW person it will surprise them. Then they will come back more prepared the next time. The drawback is it really is just a matter of time before bullets start flying whether from the mobsters or from a citizen defending themselves.
Rerun the scenario a few times.
I'm not sure what the correct response is.