OK, before this gets out of hand....
I'll admit that I am working strictly from memory and that memory set is about 40 years old. I may be remembering a shift from "low blower" to "high blower" instead of a completely disengaged supercharger. Even in that case, temperature remains a significant variable in power output of the engines. If "low blow" is the norm and is required to achieve normal power output then power output will be reduced at high ambient temps. I could probably have avoided this misunderstanding by saying "carburated" instead of "normally aspirated". In any case, increased temperature equates to increased density altitude which equates to decreased power output. While this applies to any "air breathing" engine, it is more critical in recips than in turbines. As to the usefulness of superchargers used only above 10,000', the Electra 10-E had a service ceiling of 19,400'. The 10,000' limitation was self-imposed based on AE's decision not to carry oxygen. For comparison, the T-29 had a service ceiling of a bit under 24,000' (the Convair 440 lists 24,900' but we were a good bit heavier due to installed military equipment).
Sorry for the "low blow"/"no blow" confusion (which is totally the fault of my memory) but the basic consideration still stands. I don't honestly think temperature had much (if any) effect on the final outcome. I've seen nothing which indicated AE and FN ran out of gas early. At the same time I believe in examining every realistic possibility and temperature is certainly a contributing factor in recip engine performance.
Thanks for keeping me honest!
William