Presumably, this also will make further research on patients in this state harder, since they are potentially savable and can be harmed by some interventions.

Whose brain is it anyway?

The tougher, ethical question is whether this actually would help the deceased person, or (assuming it works) even bring about a new person.

Personal identity is generally assumed to involve some form of continuity. For someone to survive, we are generally discontent with mere bodily survival, there has to be a person with some psychological continuity too.