Whatever it was, changing the Apple ID password changes something on Apple's servers, and if they have the old state they can change it back.
The only two obstacles I see is if
1. Apple deletes info from their server on password reset
2. The phone was on, and already received the message not to try to sync anymore because of the password change
You missed the entire point of my post. If I was designing a protocol I intended to be secure, I would add code that would fail if the password was changed and then changed back. I'm not saying Apple did this, but it's entirely possible they did.
The only two obstacles I see is if
1. Apple deletes info from their server on password reset 2. The phone was on, and already received the message not to try to sync anymore because of the password change
Both seem unlikely but possible.