To quote the professor:
Yet that’s all it shows: People suddenly feel that their phone is slowing down. It doesn’t show that our iPhones actually became slower.
And really, if you want new functionality - which requires new code, are you telling me it doesn't make sense that it will take up more memory and CPU cycles, and therefore "slower" ?
Unless someone finds a "if old phone, wait() and wait more()", even the "optimizing for new phone" argument is bullshit, because Apple pushes out an image specific to your phone (i.e., iOS 6 for iPhone 4 is different from iOS 6 for iPhone 4S is different from iOS 6 for iPhone 5).
Why is everything a conspiracy theory with you?