That was my thought from reading this article. No need to fire blanks in a rehearsal.
Even so, "cold gun" or not, only an idiot would cock the hammer, point the gun at a person and pull the trigger. It sure isn't rehearsing when you do that to a crew member and not an actor you're scripted to "shoot."
One of several dozen safety violations by the crew.
Prop weapons are supposed to be unloaded during a rehersal which state is supposed to be personally verified by the Armorer immediately before any activity.
Weapons should only be loaded (with blanks) by the Armorer, and only immediately before filming begins. They are supposed to be unloaded and cleared immediately afterwards.
All weapons and ammunition are supposed to be under direct personal control of the Armorer, and stored in a secured location when not in use for filming and rehearsal.
There was no reason to permit live ammunition anywhere on this set.
The list of violations goes on to the point of tedium. And there had been at least two previous negligent discharges of firearms on that set.
Baldwin, as Producer is ultimately responsible for the negligent lack of industry-standard safety procedures, announced and enforced, and the death that resulted.