We are still talking about branishing a weapon...moving a physical altercation into a potential deadly altercation. I am sure the post is missing some details however; we are talking about a road rage incident (very common where I live). I will assume this was a male against male, one wanting to fight the other. Don't see the disparity in force to justify the drawing of the gun however; I was not there.
Disparity of force? I have not heard of that in a while. In Texas the requirement is a reasonable fear of death of serious bodily harm (and not in the furtherance of a crime).