Would that be having or lacking physical mobility, or mental energy?
Recollections of Shelia from friends, family and acquaintances differ on varying scales from March 1985 up to the date of the massacre. One one hand she is lethargic, vacant, distant, on other occasions she is actively seeking work and planning holidays and having dates with other men and enjoying a social life.
I'm guessing this is all part and parcel of Shelias medical condition. Good days and bad days. A cornerstone of the guilt argument is not just about her being unable to overpower nevill and being unable to operate the rifle. It is also down to her not having the physical capacity to even attempt such a feat. Adam often had made reference to this as of recent saying Shelia couldn't do it because she was a " mouse to the slaughter" and June cooked food for her.
My personal opinion is that I think she had the energy to do so. Whether she did or not is an entirely different matter of course