While we will never be sure, I wonder if the 10 Reverse/Drive shifts at the beginning of this process somehow opens the system to accept new instructions? It is a sequence that wouldn't be duplicated in normal driving and it's hard to figure what value it would have in programming shift behavior.
Maybe instead of reconnecting the battery, following this protocol would be helpful even for cars that have been driven considerable distances since new or reflash. One could also position the car near a highway to perform the whole process seamlessly.
Noahsfocus, thanks again for posting.