Bone meds prior to spinal fusion

I had seen a doctor recommended by my PCP to explore injectables - spine is -1.9 and hip is -2.3, worse than scan two years ago. I was on Fosamax, Boniva, for about 10 years, off for about 5 yrs then on Actonel for 2 hrs and have taken no meds for 5 years. I was told I CANNOT take bisphosphonates again and the ONLY thing I can take is Prolia. After reading side effects and because I need to be out of the country for a month I deferred since I don’t want to begin anything new in case I get side effects. I recently saw a spine surgeon re my spondylolisthesis and I’m not ready, aka not in enough daily distress, to opt for a fusion yet but he said he’d want me to do Evenity before he performed surgery to optimize results. Does this make sense to any of you in terms of what I have been told I can and cannot take?