It does beg the question of why there were live rounds on the set at all? What practical purpose would they serve? If they wanted to show live rounds hitting an object, those could be shot separately by experts.
IMO, any adult who takes possession of a gun, especially a gun they didn't load themself, has the responsibility to check the load condition and the ammunition. Revolvers, like you'd use in a western movie set in the 19th century, are especially easy to check.
Just speaking for myself, whenever I use a loaded gun I'm acutely aware of everything about its condition, where it's pointed, whether or not there's a round in the chamber (for semiautomatics), and how many rounds are in the gun. Given the damage even one accidental live round shot can do, it is difficult to understand a person just trusting someone else to execute their responsibility perfectly, and pointing a gun you haven't examined at someone else. So I'm of the opinion that Baldwin can't be completely innocent.