Predators IRL do tend to attack clearly weak or weakened rivals for the sake of assuring their dominance and greater access to prey.
Any show of weakness between predators will trigger a conflict, because it's just a too good of a opportunity for a healthier one to take and get rid of competition.
Though the cannibalismn part I am not sure, while some animal may practice it, I can't really recall scenarios similars to this of taking advantage of a weakness to get rid of a competitor and then eat it, at least between competitors of the same species.