This person happens to be unusually good at reading people and has been briefed on Merrin in particular.
So before they get to the command center (once he's correctly figured out how to get there inside the hospital, if Merrin doesn't correct him), he'll ask her to wait a quarter-minute and duck in ahead of her.
Then he'll inform everybody present (physically or remotely) that he infers medium-confidence that Merrin is pretty fried from her twelve-hour emergency shift, and possibly nobody should talk to Merrin directly for a few minutes unless she initiates conversation.