Your reasoning sounds logical but at this point you have no idea if your bone metabolism is normal even after the surgery. Your CTX isn't exactly low so you have some bone breakdown going on. Estrogen also plays a role so if you are on HRT, that is another factor that could help you retain the bone you built on Evenity. At 70, you may also have age-related bone metabolism changes that will prevent you from retaining bone.

I think your doctor is being reasonable in recommending a short course of another medication to prevent additional bone loss. It's not a given that everyone loses bone after Evenity but some do so the protocol is to follow it up with a bisphosphonate or denosumab as a risk reduction strategy.

As an MD, do you have access to other sources of information? This is a laymen's site and no one here is an endocrinologist or rheumatologist specializing in osteoporosis. If it's an option to get more opinions from your peers, especially ones that treat osteoporosis, then I think that might be a good direction to go.

For reference, I am a former RN who's had osteopenia/osteoporosis for 11 years (starting at age 53). I fractured while on a bisphosphonate, HRT, strength training, good diet, etc. I am on Evenity now. By no means am I an expert beyond what I've learned through my diagnosis and treatment. My parathyroid levels have always been normal. My only risk factors were family history (my dad had severe osteoporosis) and age.