I think the highlighted part of the story is the key, the runner was making an attempt to get 2nd, once trucked the kid figures that there's no way he'll make it there, so he moved back to first, 12U ball it's unlikely he'd know the rules well enough to realize he likely has a "free pass" at second if he's thrown out by anything but a huge margin, so in his pre-adolescent brain, "I'm going to make sure I don't make an out"