That is a real stretch. A guy running away cannot and would not blindly shoot in a direction about 180 degrees in the opposite direction.
Who can’t shoot over their shoulder?
It’s easy if you don’t care what you hit.
I just tried it with a BB pistol and I had no trouble shooting directly behind me.
Heck, it doesn’t need to be direct, an officer or civilian would just need to see the barrel pointed back towards them.
Then they can fire at the perp.
He’s using a mirror, but he cares what he hits.