I'm usually all for having intelligent unit AI, but wouldn't this be overstepping its boundaries a bit? If you want your artillery to hold their fire, you can just... you know... have them hold their fire. If some dude jumps in front of your squad, everybody with a gun is going to try to turn him into a chili-like paste of ex-human goo, unless they already have specific orders not to. The behavior you're talking about would really only make sense for a hive mind where all the units know instantly who's going to do what, like a faction of robots, bees, or robotic bees.