It's not child labor, it's an age-appropriate-developmental-sorting-activity. And at the very least occupies her attention for 4 minutes.
I hope she's still happy to have this chore years from now. I have been emptying the dishwasher for as long as I can remember. Seriously. Here's proof, circa 1981 or so.
Certainly I was also in a "paparazzi avoidance" phase here, I am sure I was thrilled to help out at Nana's!