The failed experiment on the Headwood man (who seemingly dies or fails to reanimate properly in the fraught timeline of the episode) serves as a memento mori. The characters are trying to cheat death, but the train is a closed loop where death is constantly recycling life (as seen in the grim recycling of resources). The episode suggests that while the body can be preserved, the soul and the social fabric are far more brittle. The "treatment" that saved Josie stripped her of her autonomy, suggesting that in this world, preservation often comes at the cost of humanity.

The Engine and the Anvil: A Critical Analysis of Snowpiercer Season 2, Episode 5

: Back on Snowpiercer, the black-market leader Terence threatens to expose Josie Wellstead (who is secretly passing intel from Big Alice). Under pressure and following Zarah’s advice, Layton orders a reluctant Pike to assassinate Terence. The act leaves Pike devastated, leading him to shave his head in a symbolic "shedding" of his old self.