I have never heard of a single being used as a double. With the size of the room I don't even know if that's possible.
Singles in Morgan are located at the end of each hall and yes, he will be on the same floor (and share the same bathroom) with everyone else. Morgan is L-shaped; on each coed floor boys are in one arm and girls are in the other.
By the way, if he didn't specifically ask for a single I would double-check how much you are paying, as it is a few thousand dollars more than for a double.