Baldwin was also a producer of the movie.
I am not sure what the rules in the movie business are regarding when you represent both roles (actor and producer) and whether they (partly) for safety
The next thing is to be considered, when did this incident happened. It was in the middle of a filming. He was playing the scene and it was filmed. It would be different if it was during the Coffee break. Taking a gun and pointing at people isn't considered healthy :)
Even if Baldwin needed to practice drawing in front the camera there was no reason to have a human there, and he 100% knew it is a safety breach to unnecessarily fire even a prop gun at a human when not part of the scene, but decided to lazily break the rules anyway betting with someone elses life it would be ok.