In the end, you rely upon one single guy who will view the issue, and make a split-second decision. You can arm-chair quarterback all you want, but if you weren’t there...you can’t say much. I’m betting the guy who made the decision never expected this type of scenario to unfold and it was simply luck on the events of the day.
If zoos don’t want all the bad PR...then build enclosures that no one can fall into or climb into. It amazes me that we don’t have a hundred of such events to occur each year with nuts trying to climb into some pit with tigers.
But yet, far from a hundred such events per year, we have none for many years. What is lacking in your calculus?