I agree with your reasoning, BUT my email confirmation says "Delivers By: 09/21/2012" while the above website says "Expected Ship Date: 09/21/2012".
Pretty big difference between the two, if you ask me.
its been stated so many times on this thread and the OP says it..... read people, last year on the 4s it said the same thing and everyone received it on launch day.
itll all be good.