And how much incoming fire does the average HEMS helicopter draw?
To me there is a huge difference between training someone who is trained to work on helicopters, in helicopters as part of mission essential crew and exceeding the requirement for "straight and level" to zero speed situations to taking someone from a totally different prpofessional environment and allowing them to play with the controls "just because it seems a good idea".
Having flown HEMS myself I never felt that their RT course and map reading made these outstanding guys even remotely close to being able to manipulate helicopter controls. So part of their job was to ensure their pilot was fit to fly and when in doubt, refuse to fly.
The risk of something bad happening when the HEMS crewmember exits the helicopter rotors running at the scene of the incident and knocks the controls is a lot higher than the chance of the crewmember saving the day because his pilot becomes incapacitated.
Horses for courses. The operator clearly feels it a waste of money to employ properly trained copilots for the job. If you feel that you need an extra pilot, that is where the fight needs to to be taken, not "solved" at workfloor level.