Gold parked right next to Cain's SUV in order to confront him. Yes, Cain did drive away after he got out of the SUV and shot Gold after attempting to rob him. Gold forced the confrontation. Cain was in the SUV with the door closed when Gold pulled up. Had Gold stopped before he reached the SUV or went past it and stopped, I think Cain would have driven away. He showed every indication that he was done with the action when he took the purse from the woman and got in the SUV.
Look at the first video. Gold drives past the street the confrontation occurs on, sees Cain dragging the girl down the sidewalk, puts his car into reverse, backs up and then drives down the street to confront Cain. At 18 seconds into the first video you can get a good look at how much room there is between Cain's SUV and the car parked in front of it. Now look at the location of the car parked on the other side of the street. I'm sure Cain had to think that Gold was trying to block him in.
Looking back at the first video. At 25 seconds Gold walks directly in front of the SUV, places his left hand on the hood and he's holding something, (Cell phone maybe?) in his right hand.
Unfortunately we don't see what happened next on either video. There is a gap on the second video and at 44 seconds we see Gold bent over the woman who is down on the sidewalk. At 45 seconds the door to the SUV opens and Cain exits the vehicle with the TEC-9.
You can't tell for sure from the gaps in the video, but it looks to be like Gold was looking for Cain, he drove down what appears to be a one way street from the wrong direction, parked in the driving lane next to the SUV in what looks like an attempt to block it in, then confronts Cain.
Educated guess on my part, but it certainly looks to me like Gold put himself in a position where Cain felt that he must deal with him or he wasn't going to escape. If Gold had simply pulled in front of the SUV that was parked in front of Cain and watched, there probably would have been a much better outcome. Or he could have driven past Cain's SUV and observed from there and that probably wouldn't have alerted Cain to the fact he was spotted.
The girl was down on the sidewalk and Cain was in the SUV with the door closed preparing to leave the scene when Gold confronted him. Gold had no idea what he was getting into and had no idea that Cain was armed.He charged in, didn't keep anything between himself and Cain and got shot for his trouble. He went from being in a position to aid the girl to becoming a victim himself because he didn't think through how he was going to handle the situation. Cain didn't need a gun, he could have come out of the SUV with a knife or an empty handed attack and Gold wasn't ready for it.