Also, wasn't this one of the fixed points in history that couldn't be changed? I feel like that was mentioned somewhere in the line, but I have no idea where (time to rewatch the series, I guess).
Here's my interpretation, and yes I am still using the old numbering for doctors:
The doctor never used the moment in the first place. This episode never actually changed anything, rather it explained what really happened. Gallifrey was locked in stasis in a pocket universe, the daleks destroyed each other in the crossfire, so from everyone else's point of view, it looked as though the Doctor used the moment.
The war doctor was about to press the button when the other two doctors showed up, found another way around, then the war doctor regenerated into Nine immediately after. Since Eleven is the only doctor to remember this series of events, The last thing Nine remembers is when he was just about to activate the moment and burn Gallifrey, causing him a ton of guilt that lasted until Eleven saw this happen.
So, all of this happened in the first place, but the war doctor and ten never remembered it, and everyone else simply thought the moment was used due to the results.