Holding a rounded handle with a rectangular profile slider is inherently unstable as it's extremely sensitive to the pinch point.

And the bowl has a radius that make orthogonal grip impractical.

But it has two pinch points. There are two separate grippers. Look at how it uses scissors.

If the radius of the bowl is that big it's too big for anything one-handed (with a reasonable size hand). So use two hands, like people do.