Mickey: I understand your point, It is possible with a bow and /or a rifle of any caliber to make a poor shot. Nothing to be proud of but only a fool would consider the possibility of the event. At that point yes I would FOLLOW my PH ( provided he allowed me to) with a rifle.
Do I expect or rely upon him to stop a charge if I'm standing there with a stick& string in my hand....surely I do. IF his gun fails or he himself fails....well then guess I'm a grease spot in the grass!
It is afterall DG hunting, and I know that going into it...that to me at least is the draw of the hunt. If a PH or tracker looses his life along with me well that is a hazard of their choosen profession,is it not? No different than should I loose mine in an industrial fire at home at work.