If there had been a real threat, I think people would have a better argument than the car crash scenario. A casino can’t be responsible for your car crash - that’s on you.
But they do have a responsibility to provide a safe playing environment - if they fail there and you get injured as a result, I think you’d have a legitimate claim. Or at least more legitimate.
But here, there wasn’t actually a shooter - there wasn’t actually a threat. People all panicked at once, over nothing, and they had a bit of a riot. It’s tough to blame the casino for that.
Maybe they could argue that the casino’s room was unsafe in and of itself - insufficient exits and such. But I wouldn’t want to pay a lawyer to go after that long shot.