The uncircumventable empty task switcher screen is one of my primary concerns too, it's actually one of the things that could make me stop using the N9 in the future. With a UI that is so minimal, every illogical extraneous input action has a major impact on the overall user experience.

In another thread i called the empty task switcher the "the ultimate UX dead end", especially when closing the last open application and getting 'stuck' on this screen. Closing something means you want to be able to start something else immediately, or at least get back to your 'home' screen. Although the app list screen is only one swipe away, the existing approach is very counterintuitive and dissatisfying: one swipe with 3 homescreens is still 33% useless interaction.

Personally, i would prefer to see it not being a part of the horizontal swipe cycle at all, but invoked by another method. For instance through the swipe-up-hold method which now shows the 4 app shortcuts. I never use those, since they also feel like a UX mistake: a good (simple) interface should provide one method to start apps, not one and a half baked pseudo-method.

But regardless of the method, it shouldn't be visible when you're cycling screens with no open programs, that's for sure.