The more diffuse light of the small flashlight isn't enough to render her completely solid. He's got her trapped, and it's clear when she gives up on the trick and starts struggling again that she's definitely in pain, but for the moment that's as far as he's getting. In this state her body compresses rather than cracking and breaking in response to the unrelenting pressure, ready to spring back into form (however painfully). He's going to need a brighter light like the enhanced bulb on the rifle scope if he wants to kill her without having to pin her like this until dawn. Meanwhile she is doing everything in her power to get free, kicking and spitting and squirming.