Agree on almost all counts...

They weren't filming and Baldwin was screwing around with the gun...

What makes that even more interesting is, I’ve never in my life been on a show where they’ve used an actual gun for rehearsal. That gun is supposed to be rubber and it’s a big deal when a real gun is on set. They call a safety meeting before the gun leaves the hand of the armorer. Or at least that’s what’s supposed to happen. BUT the bigger question is how did live ammo get on the set and inside that gun??? I choose my blank loads on every job I have with a gun. 1/4 loads up to full loads. I’m shocked at how many balls were dropped. Including on Alecs part and the director. But only on Alecs part as an Actor, not a producer. Maybe this will make Actors stop asking for producer credits. It’s just a lame title that means nothing in the end. On Vampire Diaries 2 actors had producer credits but neither one were actual “producers” if that make sense. I was a producer on Vampire Diaries too but again, mine was a nothing title just to keep me around for the later seasons. As an actor though, he should’ve known better but he’s certainly not to blame. It’s the armorer and 1st AD but also the line producer, who didn’t listen to concerns and I believe they had guns go off accidentally earlier on that set. The camera crew walked off the day before due to safety issues. That line producer should’ve shut things down or done something earlier. Too many people dropping balls. I mean sadly, the DP should’ve said something about the gun situation too. They have lot of say on a set. They’re the most respected person besides the director. The whole thing is a sad situation for everyone. I don’t know if you’re familiar with he Sarah Jones death but that was also sad and the director got put in prison for it. As he should have. The Line Producer and 1st AD also got charged
”Midnight Rider” filmmakers charged with involuntary manslaughter in Sarah Jones death – Boston Herald

If it were you or I we would be in prison already. I have been following the Legal Opinion issues in this case and they all agree it was second degree manslaughter (non-intentional). That is a crime.

Yet Michale Massee walks a free man to this day after shooting and killing actor Brandon Lee on a film set with a prop gun. Perhaps, they looked at the filming rules and safety protocols, who’s responsible for guns on set and realized they didn’t have a case?

That prop gun had the correct blank cartridge in the chamber. Unfortunately, there was a fragment of a fake "real looking" cartridge left in the chamber from a previous shot, where they needed to "see' the bullet...

That was what was propelled out of the barrel, killing Lee...

Even if the shooter had checked the chamber, he would have seen the proper "blank" round.

From what I've read, they weren't in actual "rehearsal".

Yes, they were on set, but they were not rehearsing. Baldwin was sitting on set, "practicing" his cross draw. They were NOT rehearsing a scene...