Often the bees will supercede either shortly after or before swarming, agreed. With a clipped queen that is usually the case that she is a previous year's queen. Remember queens were good for two or more seasons, not so long back. But the idea that swarming is because she is past her best just is not true.
A queen is, by your definition, past its best after simply overwintering. I say, she could have continued for some time at the peak of her career, and might likely have carried on and founded a new nest - were she not clipped. You, now modifying what you previously stated as categoric, is pleasing to note. Rules only have a few exceptions
Regards, RAB