Starfinder Society Roleplaying Guild Guide p.29 "The ally
does not participate in combat, cannot be killed outside of combat," - but that is for Ally Boon.
What about my Surviving Companion (Slotless, Vanity)? He doesnt have any actions (like basic hireling does) - can he die from area effects or radiation?
When asking questions about a specific scenario, it's best to ask over in the GM Discussion Forum. It helps avoid spoilers, asks people who have already GMed the scenario, and the authors will usually chime in with their views.
HERE is the thread for this scenario. I see that someone else asked this very question earlier today.