Everyone has a bad day at work sometimes. You just don’t have the motivation to complete the tasks at hand, you can’t remember anything you should be doing, and you just cannot be bothered to take it seriously.
It happens to the best of us. The person at this museum was obviously having one of those days when they had to put this really, really old skull on display. While they probably knew that they had to give visitors a little more information, they just didn’t want to. It was going to stay like that because it’s close enough.