I agree with you that Oxygen is a medically prescribed drug, but it is not something that should only be administered by a Emergency Medical person.
Obviuosly this person was Cyanotic at the point that they were caring for her, and no matter who you are or where you are, if this condition is obvious, and you have a cylinder of oxygen at your disposal, then oxygen is the immediate thing that should have been given to her.
I am a retired Registered Respiratory Therapist, and fully understand the complications of Oxygen in high dosages knocking out the respiratory drive, but at the point she was, she did not have a chance without immediate oxygen therapy.
It is indeed sad that this happened, and the manner in which it was handled is yet to be determined.
My condolences to this family.