Despite clearing the building and double checking for enemies and cryptids, Atkinson didn't leave Gordon's side the entire time. As the only engineer in their team he was the most valuable member for the mission. Even if they all died, as long as Gordon managed to fix communications and send a message back to base their mission would be considered a success.
But this didn't mean he didn't care for his people's lives, just that for him the mission would always come first. It wasn't for nothing that he was made a captain despite being old already when he acquired his trait, as his superiors considered that even if his career was short lasted it would still be well worth the resources they invested in him.