It will be for the medical crew to do scene management and actually eyeball where the incident is in relation to the landing site. The medics sit on the left side of the aircraft with the stretcher fit on the right.
As the Captain & flying pilot always sits on the right, he would be doing the landing. The LH seat pilot is in charge of the navigation and operations/ ambulance frequency radios. The visibility in the front of the Explorer means that the flying pilot can always land the aircraft (sometimes the LH seat pilot will open the door to clear the tail area).