Does this prove that a complete evacuation isn't necessary before colonoscopy?

My friend’s boyfriend has been in the hospital for a month. He has a bad heart and finds it difficult to stand up due to an infected spine. They wanted him to have a colonoscopy but, instead of having to drink a gallon of chalk water or take a bazillion pills all he had to do was have an enema the night before and some milk of magnesia. Does this not offer at least some proof that all the other preps are overkill and not needed? They could not be up with him all night while he got his colon cleaned out . He has to be helped to the bathroom.