You seem to have a great relationship with your GP, probably because you are good natured.
I have a pathologist begging for my bones, when I'm done with them. My brain is committed elsewhere.
I'm not in complete sync with you, ethically, regarding economic feasibility as reasonable for denial of medical care, especially for the elderly, though great caution should be given to a surgery that might exacerbate any existing comorbidity.
Even the value of the surgery cannot be measured in $signs. The knowledge and skill derived from performing surgery could well be what saves the next (younger) patient.
Bless your health.