But why tho? Does a cop keep their gun holstered until absolutely the last second? No! They aim at you at the first sign of danger so that you think twice before you do dumb stuff. Why wouldn't that apply to civilians defending themselves or their property?
Point is they SHOULD keep it holstered until it's the only option available. There's a case to be made for training and accountability, but at least in the states that goes out the window. Your average cop is neither trained nor accountable,and certainly shouldn't have a gun. That's another argument though.
All of the warnings can be done before a gun gets involved. You can warn that you will defend yourself, that you have a firearm, etc. without brandishing it. And still, firing the gun and not hitting something important, in a high stress situation, regardless of level of training can't be done safely and reliably.