it is not too much of a logical leap to imagine a former Boeing 767 captain finding employment at the controls of a KC-46A tanker, for example.
While this sounds logical, it may not work so well in practice. Your average pax hauler 76 Capt is at least as old as your average 0-6, while your average tanker AC is in his twenties. A tanker AC may be told (no contractual protection) to T/O 18 hours after his last sortie landed and to fly up to 150 hours a month. It’s a young mans’ game for good reason. Crew resting in tents, eating MREs, having that rest reduced for operational necessity, dealing with bs from a squadron commander in his mid-30s who came up in a different weapon system, etc. Military ops run on the backs of young captains and lieutenants who can burn the candle at both ends all around the middle for years on end. They get burned out for good reason.