I am not totally convinced he did not walk out and have an accident on his way back to camp.....
However, I have to admit the most logical explanation would be the bin and the lorry. So was C being in the bin a result of his bad decision or of foul play. I am leaning towards his bad decision. I base that on statistics. the area has a low crime rate, especially low in homicide..more likely to be simple assaults, maybe a mugging, perhaps a more serious battery in some cases. I know its not unheard of, but he was not in an alley in NYC or even London. He was in BSE. If there was a "beat down" by a group even, they would more likely just leave him there, not place him in a bin.
I do think he was at least unconscious at the time the bin was collected. So a serious assault could cause that. I just think it is not likely. Accidents are usually a series of events, where even if just one thing had been different the accident would not have happened. I think C decided he would hop in the bin to wait for sun up. I think he might have done this before. This time he slipped climbing in, fell hard and knocked himself out, or perhaps even broke his neck. In either case, he did not hear the lorry. He was not so drunk, he would have slept through the lorry collecting. He might have also had a medical emergency, such as a seizure, again leaving him unconscious or compromising his airway. Now we have one more complication, why the bin reportedly weighed 33 lbs. I think it was more like 200 lbs.