In fact if he’d left the Outflow valve switch in AUTO, the system would have itself closed the outflow valves. In this latter case the FE would have had no awareness of the valves being physically closed off completely and thus have no cause for any alarm or concern.
You have brought up some god points Unctious but I doubt if the FE would not have noticed both outflow valve indicators showing closed in Auto. Those indications would have certainly aroused my concern, not that it mattered at that stage anymore unfortunately.