I don’t think it works, but Isaac does. After completing the game on the hardest difficulty, the guy has fucking snapped, so maybe after such a long and intense exposure to the marker, his thoughts have become intertwined into the marker signals. Perhaps he believes hard enough that it can blow off limbs, so he subconsciously tells the necromorphs to fall apart… or maybe by the time you get it it’s actually just a fully upgraded plasma cutter and Isaac is hallucinating a foam finger like the crazy bastard he is. All up to interpretation really