I would agree with you 100%. Costs and Benefits must be measured, and measured correctly at a split seconds notice. If one is not willing to accept the possibility that they could die while going into a hostile situation against (most likely) superior firepower then those are the sort that should stay put, and if that thought never enters your mind then you also should stay put because you are not thinking clearly.
Either way a cell phone call would be a great help to the first responders as your location and other such important variables that may not be available to them. A clear description of yourself and if possible the shooter is also a major priority. And above all do not argue with the police. To them anybody with a firearm in such a situation is suspect, and rightfully so.
I am going to be CC to make my wife feel better, because she knows that in that type of situation I would help those I could, regardless of being armed or not. Is that smart? Hell no! But I have heard the accounts of various shootings. The wounded if found by the shooter typically are executed. Knowing that, I will not stay and hide, but niether will I act like a baffoon and put on my cape. For I am willing to die doing such things if need be, however that is NEVER my first choice.
Nobody can make that choice for me, and nor will I make it for anybody else.