I would grant that "fretting" was poetic license. Consider that the life-saving robot must continually evaluate all factors.
Let's say I was closer to a lava flow than you, but your path was on a slightly more direct course into it than mine, and the robot is located at the lava's edge midway between both of us. I will hit the lava in 30 seconds, but you will hit it in 20. The robot needs two seconds to have a high probability of saving someone, but one second is enough for a moderate chance. Factoring in the motion required, the chances of saving us both is high. As you are in more immediate peril than I, it should intercede on your behalf first, so the robot starts to move in your direction. Now, I change my course slightly so I will hit it in 15 seconds. The robot still has time to save us both, but the chances are slightly lower. It moves on a path to intercept me first. You then change your path so you will hit it in 10 seconds. The chances of saving us both is now only moderate, but still possible. So the robot alters its path again to save you first. Now, we both steer directly toward the lava, with only one second to intercept for either of us. The robot's continual path changing introduced so much delay it was no longer in a position to save either of us. We both die.
To the outside observer, it fretted, but the algorithm made continually logical decisions.