I agree, that being said I wonder what a good name would be.
Private? Other browsers also use this name, but regardless this isn't any more private than any other browser instance.
Container? Way too techno mumbo jumbo.
No Cache? Even worse pig latin.
Boxed? It's layman speak, but it doesn't convey the cacheless nature.
Forget It? No Memory? Amnesia? Cacheless to be sure, but also still open to misinterpretation.
This is an interesting exercise.