I'm not sure where I stand on it with just the info in the link. Stopping to help is definitely "Good Samaritan". The rest would depend on what really caused further interaction with what appears to be hoodlums in the other car.
I would, again with the little info provided, tend to agree with gunsmith regarding a lack of training for this situation once his gun came out, and then apparently back in the holster while multiple threats were still active.