So dumb, in other stories the test had bad results because the magical pool was so big and it could only see the first 2 numbers that made it look like it was super low or zero, but in this case the gauge made full circles before stopping.
I would understand not accepting a failure, but the mother DID notice the gauge making multiple turns, it would cost them nothing to reset it, test themselves and then the kid and verify it did make 11 turns, a real mother at least would have never discarded their kid so easily, EVEN MORE if there was even just a speck of doubt in the result.