Zumwalt's medium carriers as a mobilization reserve

Would Zumwalt's proposed medium aircraft carrier have prevented the Nimitz class?

No; it was intended to complement nuclear carriers with cheaper conventional hulls that could enter reserve and return during a surge.

Nuclear carriers could perform more missions and cost less to fuel on deployment, but their reactors and specialist support make inactive reserve status wasteful. Zumwalt's conventional medium carriers could supplement the nuclear fleet, train near home, and provide mobilization hulls during a surge. A reserve force would also prevent the kind of availability gap that follows when an already small active fleet has just completed a major surge. The panel contrasts this requirement with commercial accounting: a business may keep one asset on call, while a military service needs assets operating, on alert, in maintenance, and ready to replace one another. The broader lesson is that armed forces need redundancy for wartime demands even when inactive capacity looks inefficient in peacetime.