This is not how it is going to work. Where did you get that information?
Quote from the pre-order page (after you click "Add to cart"):
NOTICE: Your order contains at least one Pre-Order item that will not be charged to you at this time. You will only be charged for the items in your cart that are available at this time. Your preorder will be saved in our system, and when the product becomes available, you will be charged and notified.
Beta = becoming available
Well, I could ask you the same thing: where did you get that information? There is no mention of beta in the text that you quote, so it is kind of logical to assume that product = finished game. Then again, if you are so sure about that, I'll believe you, it's not like I know anything about how this thing works.
Oh, and let me rephrase my statement: this whole we-will-charge-you-when-we-make-a-beta is kind of annoying.
Since some people have actually preordered the game some months ago, the situtation does not change fundamentally if you get charged in September. It would simply be more convenient to have the option of paying up front. Not that I do not understand if for some reason it would be hard to implement. Simply voicing my opinion.