Hard to say what happened here, but as Ambulancedriver hints, overzealousness to teach procedures of dubious value aside... I can see how the hospital would possibly be in a catch-22. Brain injury can cause the victim to be combative. And if the hospital misses a neurological or spinal problem and the patient dies, or suffers a permanent disability or motor deficit, they could be on the hook for millions in malpractice.
Even acknowledging a smidgeon of relevence in the first part of your post, how could getting conked on the forehead with a 2x4 conceivable lead to a spinal chord injury that would in any way be revealed by a rectal examination? A rectal exam at best would allow the doc to manipulate the coccyx area and the sacchral area -- which are (in spinal terms) rather remote from the head.