BGF, I don't understand your point. Patients have different diets - the diet offered to an obese patient, a patient with anorexia, a diabetic patient, a newborn baby and a 4 year old child will all be different from each other.
The hospital has made food available to the baby - breast milk. Part of the care of a newborn bay in hospital is making sure that the mother is capable of looking after the baby. The hospital cares for the baby directly only if the mother does not do so. So the mother is expected (unless there are medical reasons why not) to bath her baby, to change her baby's nappy, to pick her baby up when it cries. The hospital does not directly meet a baby's needs in the way it does other patients, unless there is a medical reason to do so (i.e. mother in theatre, mother too weak, baby has additional needs).
The hospital has provided the mother with food it considers appropriate for the baby - the mother's breast milk which has been produced as a consequence of food they give her to consume. If she chooses not to pass this food on the baby she is caring for, it is not up to the hospital to provide an alternative. If she cannot feed the baby, then the hospital has an obligation.