I dont get why they do this?

I'm glad he turned out not to have a neck injury. During a bad fall many things can be injured. A neck fracture may not be noticed at first and if the EMTs didn't protect his neck, moving him around could have paralyzed him. The pelvic fracture is what is termed a "distracting injury". This is because the pain is so great the injured person doesn't feel, for example, a broken arm or neck or ribs, etc. So as uncomfortable as he was, they were doing the best thing for him.