It becomes Brandishing when you illegally attempt to detain someone. i.e. chasing someone down with a truck while screaming for them to stop. You can not have a gun, in any manner of possession, if you are committing a crime.
If you read the article it specifically says that they are trying to make “pulling or showing a firearm during a dispute” legal. Meaning that right now it absolutely is not legal, during a dispute (not just a crime). They are not legally making a citizens arrest, they are responsible for understanding the nuances of the law before trying to do so, thus a dispute. They’re lucky they’re not in here in Florida. In Georgia Kidnaping requires restraint and movement. Here Kidnapping can be as simple and refusing to allow someone to leave. But that’s beside the point.