This is probably a bug, but I can't seem to save Chris. I stop Raum from slicing Chris's throat but in the next scene he's dead??
I don't know if it's this that you're referring to, but initially I also couldn't manage to save him even if Raum didn't harm him. I played around with it more and found out that if MC ignored Chris' phone call earlier then he survived and can join the team, but if MC answered it then he can survive the fight initially (I think there's a line about him making a sound as he's being freed) but he's not in the car after Sydero arrives... Maybe she doesn't grab him / wait for him to get in the car if she thinks that it was MC's fault?