I believe the question was should a governor stop the painful death of the hypothetical woman due to fluid buildup. If she is going to die a painful death without the draining procedure, how much more harm than that could be caused by the procedure? At least there would be some hope if the procedure was carried out, without the draining there would be no hope.
Yes, but how is the governor supposed to know whether draining the fluid is medically appropriate?
It doesn't take a doctor to know that if you remove food and water from someone they will certainly die unless they are given food and water again; giving them food and water cannot cause any harm worse than denying it. But in your hypothetical, how could a governor know for sure that draining the fluids could do no harm?