The pace question is worth raising. Front-loaded loss on GLP-1 compounds is well-documented and the first weeks skew numbers significantly. Guidelines vary, and what matters longer term is composition change, not speed alone.
The rebuild assumption is sound - maintenance calories plus resistance training after a cut does allow for muscle gain, including later in life if you have any base already. The fear of being too old for newbie gains is overstated; new gains from returning to a lower weight are real.