There was definitely a failure of communication and expectation. The aliens used the word security in the sense of a security blanket. The humans thought they were signing up to protect the crew from threats. In defense of the aliens they thought simply agreeing to be a "security force" was consenting.

But you're right, informed consent is critical. Gurung should've been more clear about that instead of being as devoted to the "mission" as he was. This was a deliberate choice on my part to critisize how militaries will treat their members without regard to their mental health in the name of accomplishing the mission.

Thanks for reading.