The detail is sketchy but I'm fairly sure the helpful passenger was more than simply a Flight Simmer or spotter and was well able to identify himself as such. Clearly the Captain felt his presence was welcome or he'd not have asked him to go up there. Any rated pilot would be able to handle the RT, find the charts, run the checklist, keep a look outside and act as a spare pair of eyes.
We don't know who this guy was. He could have been anything from a Cessna FI to a Space Shuttle commander but the Captain felt his contribution was valuable so let's give him the benefit of the doubt, no?