I disagree that not brining back Tuvok and Neelix would have been murder. Murder generally requires you do an act which results in the death of another person. If you do nothing (unless you had a duty of care i.e. a Doctor) than you can't be held liable for murder.
So, if two crewman were badly and mortally injured, it would NOT be murder to withhold medical attention from them? If Neelix and Tuvok were lying in a corridor with phaser burns that would be mortal without treatment, it'd be just fine, and not murder, for everyone to just walk by them? It certainly would be murder, in the Doctor's case at least, as you pointed out.
While most jurisdictions don't have "good Samaritan" laws that require people passing another who is harmed to, say, take him to the hospital, I'd say most of us would find someone who simply passed an injured person on the street, one unable to help himself, to be acting in a pretty morally objectionable fashion.
But these are crewmates on a ship, not simply stranger civilians passing each other by, and I'd guess that the Starfleet code of military justice would require them to help each other.
Anyway, this thread isn't about law, but in fact IS about ethics.