I don't see this job ever becoming an FAA licensed position.
I understand some companies are way better than others with their SOPs and operations but if a Loadmaster is part of a flight crew and that said person is totally responsible in the matter in which the aircraft loaded and the cargo secured then I'm sorry but believe these guys should also be licensed.
What if this crash happened leaving a major US airport like Atlanta, Kennedy or Chicago and the aircraft crashed in the middle of a town?
I bet you a beer that when the NTSB report became public knowledge and the people discovered anyone could be a Loadmaster (no license required with proper training) the
would hit the fan.