Maybe they were concerned that, having been dropped onto a hard pavement, there might be injuries to the baby that could be exacerbated by moving it - such as a spinal injury. There could be an undisplaced spinal fracture that could displace if the baby wasn't moved carefully, causing paralysis, for example.
Obviously I don't know what, if any, injuries the baby had suffered, but the general advice is that members of the public should not move a casualty unless the casualty is in imminent danger - ie if they are choking and you need to move them to clear their airway, or if they are in a hazardous situation and need to be moved for their own safety.