You want the staff to medicate for the patient's comfort not your own. Many families do this and it is wrong. It should have been explained to your brother that they were treating the patient's needs and not his own. It might sound harsh but it's true and often necessary for family to hear.
The staff was right in this situation. They knew she was terminal and knew the best thing for her was hospice care as this point. Your brother should have listened. Surgery, tubes, etc. isn't the way this woman wanted to go. Most staff feels the same way. They see the needless suffering the patient goes through all for the benefit of the family. The focus needs to be on the patient and you bring in a social worker to help the family deal with their grief.
Hearing someone you love is dying is so hard. In this case seeing as she went so quickly it is even worse as the family had no time to prepare. Help your brother to grieve his beloved friend. Assure him how much she loved him and how she is now at peace. Repeat that again and again to comfort him. I pray he feels better soon.