The cruise format itself is well suited to older travelers — you unpack once, and the ship handles transport between sites overnight rather than requiring repeated hotel changes and long travel days. Cabins, dining, and common areas are all on one vessel, simplifying daily logistics considerably.
What to plan around
The main consideration is the excursions themselves: temple visits involve real walking, often on uneven stone, sometimes with stairs, and in warm daytime heat for much of the year — see How Hot Does Egypt Get, and When Should You Avoid Traveling?. Discussing your own pace and any physical limitations with the operator in advance lets excursions be planned realistically.
Many older travelers manage the full itinerary comfortably, especially by pacing themselves and skipping an excursion here and there in favor of rest — the schedule is rarely so rigid that missing one stop causes any real problem.