Unless (and they probably do) the DA knows some fact(s) beyond what has come out to the public, I don't see how you can charge Baldwin with involuntary manslaughter. Basically, my understanding of the facts is that he was handed a gun, which was either supposed to be a prop or supposed to be unloaded and given the all clear language by the assistant director.
His job is to maneuver the gun in ways in which a normal person would not - IE spin it, holster it, point it AT people.
The FBI weapon report said both "it couldn't be fired WITHOUT pulling the trigger" and opps it broke while testing and DID fire without a trigger pull -- WTF?
So, absent a material fact not in evidence why on earth did you charge Baldwin? Was there a grand jury? How was this decided.
Once the charges are dismissed I would sue the shit out of the DA's office if I were Baldwin.
Now the armorer .... sure you can definitely make a legit argument that her culpability rises to criminal negligence