While the pallet destined for geographical destinations makes sense, it also might be that destinations with high population density have so many orders that it takes longer for an individual from that location to get to the front of that order line. Meanwhile, customers in less populated destinations with fewer orders, pass through the staging line quicker, get palletized, and shipped sooner.
Again, that wouldn't matter if what the Apple reps are saying is true. According to Apple reps, they are all palletized in bulk from China and shipped to Alaska (and then often times onto another US destination, such as the FedEx World Hub in Memphis, or the UPS Worldport in Louisville), where they are then resorted for specific regional delivery across the US. They wouldn't be palletized according to specific geographic destination in China if they're individually resorted upon arrival in the US, such as the FedEx World Hub in Memphis, or the UPS Worldport in Louisville.