Interaction Isn't Explicit。

During the passage of Chapter 2 there will be a moment where you will need to raise several platforms by shooting from a pistol. There will be an enemy on one of them. Kill him when he is on the platform and then shoot the cube so that the platform rises - you will get a trophy.

simply put, it doesn't matter whether the NPC is alive or dead, maybe it's bugged, it's given in any outcome.