The Jetstream can use an ambulift, and I used to use one almost daily in Highland. However, on the western isles, the service is provided by HIAL's fire service, not Highland Airways. They have some very strict rules about when the ambulift can be used, which, if I recall is no more than 15kts of wind. Try and find a day with less wind than that in BEB or SYY and you begin to see the problem.
The health board and local doctors have no idea when booking pax on travel for hospital. How are you supposed to board pax who weighed well in excess of 130 kgs, only have with one leg, are blind and completely immobile. I don't think that a Saab crew would have an better luck that the HWY crew.
Personally, I would be deny boarding to any pax who could not carry themselves from the ambulift to their seat, or if it was too windy for the ambulift and they could not climb the steps unaided. It's not the ground or flight crews job to physically manhandle pax into the aircraft. If they need that level of assitance, then get them on the air ambulance or send them by road. Its safer for all involved.