Do you work for FedEx? Otherwise how can you definitively say FedEx didn't call up Apple and tell them they can't guarantee delivery for all phones on the 24th and they need to start delivering immediately? Given the pre-ordering CF I imagine Apple is a little gun shy to more bad pub. They are likely trying to get ahead of the curve here.
Also where did I say FedEx "dictated" terms. Apple has a contract w/ FedEx. Both parties negotiated those terms. I have no idea what the terms are. Regardless it doesn't preclude either party from asking for a wavier or a change.
You said it best when you said you have no idea.
As FedEx is, and has been a client of mine for well over 15 years - I can assure you - the "load" for this delivery isn't an issue.
As for "where did I said FedEx dictated terms" - you're right. You didn't write it. But you did write "The most logical reason IMHO is that FedEx told Apple that it needed to start delivering phones as soon as it rec'd them or they might not be able to deliver them all on the 24th."
That's pretty much implying that FedEx told Apple "let us do it our way."
As another has said - server load is COMPLETELY different than delivery in terms of strategy and planning.
(pssssst Fed Ex and every other package delivery company doesn't only rely on their teams/fleet to deliver packages during the ROUTING phase of delivery)