What I thought was after we fought the mice we returned to the main room (the first room) which only had the door we came in and the east portal.
“Might I suggest we use the one in the first room,” He said and without waiting he walked back into the other room and over to the portal, “If there are no objections, I will volunteer to go first.”
I guess I'd have read the south portal as being at the end of the hall to the library not in the main room.
But if it was the south portal I'm good with it.