Josh was mistaken as a member of the Viet Cong and held captive by the psychopath Cliff. He and two other captives, Rich Atkins and Barbara Patterson, were trapped inside an empty store next to Crislip's Home Saloon.
After Cliff is defeated, Frank unlocks the doors and convinces the three frightened survivors to follow him to the Security Room. If Frank kills one of the survivors before recruitment, none of them will be willing to talk to Frank, and they become impossible to recruit.
After being rescued, he will wait in the room with the green door. When Kindell Johnson believes that there is no helicopter coming in three days, he rallies up the other survivors in the same room, including Josh, to leave.
If Frank does not stop Kindell's mutiny, Josh will leave the Security Room along with the other survivors in the same room. They will no longer count towards the number of rescued survivors.