Tom doesn't stop until Psii is well and beaten. Once he's managed the first blow, it becomes apparent - to the cameras and to the troll he's bludgeoning - that he's drawing this out, that he's enjoying the strange-colored blood and the exertion and the crumpling of bone and joints under his club. He doesn't have the desperate frenzy of someone who doesn't know what he's doing, but rather the cruel brutality of someone who could finish the job but is purposefully choosing to aim for pain rather than efficiency.

Finally, he stops, not from exhaustion or mercy but because he's become bored with this, because he feels the injury done to him (the insult) has been adequately repaid and he would really like to get back to Molotov before it's dark. He considers waiting for the cannon, but his clothes are wet with Psiioniic's blood and melted snow, and so he decides instead to opt for assuming that if Psiioniic survives this it'll be an earned miracle.

"Never seen one bleed that color before," Tom says, kicking at the Psiioniic's face. And with that, he limps his way back into the trees.