The Hippocratic Oath comment was related to The Breach, which is why I specified it didn't apply in The BreachThe Hippocratic Oath doesn't really apply in The Breach. It says do no harm, and do what you can, it doesn't say anything about treating a patient against their will. Plus, there is no Starfleet in Enterprise, Phlox was simply an Alien Doctor on a Cultural Exchange.
Babylon 5 dealt with a similar matter. An Alien family had a son with a breathing problem that was killing him. The Doctor could fix it with a simple operation, however, the family's Religion didn't allow cutting/surgery, and so they refused to allow the Surgery. The Doctor went to the Commanding Officer to ask for permission to do the surgery, the Commander ordered him not to do the surgery unless the family agreed. The Doctor did the surgery anyways and the boy was fine. But, the family believed he was no longer pure and they killed him
Hippocratic Oath does apply when Phlox chose not give the give the cure to the Valakians. I wouldn't want to be treated by a doctor who can hold medication I need to survive on a whim.
I am talking about the Hippocratic Oath in general and Phlox breaking it in "Dear Doctor" is pretty relevant to the topic.