IPad Activation Lock with Mystery Email?

Question

Hello all,
I have been searching online now for 2 days trying to find an answer to this question but haven't yet had any luck.
My father bought an iPad, brand new from Best Buy in January of 2013. I was with him. He has loved it and used it almost every day. Recently, he upgraded to iOS 8. About 5 days ago, my father decided to update to iOS 8.1. When he did, the "Plug into iTunes logo" showed up and he did as instructed: plugged it into the computer/iTunes. When he did, iTunes told him he needed to restore it, which would erase everything on his iPad. Not wanting to do that, he ejected it from the computer.
This is the part where it gets a bit confusing. The iPad then told him that the current iPad was registered to someone, and if that someone was him, he would need to put in his iCloud information. Not a problem, as he put in iTunes account username and password that he would frequently use to buy apps, movies, or songs on his iPad since January of 2013. But the iPad informed him that the information was incorrect. So he changed his password, doing the password email reset link on the computer, thinking he may have put it in wrong. Still no access. In fact, the iPad said that the iPad was already registered to another account. His iTunes login that he had used for all the purchases was [email protected], but the iPad said it was registered to [email protected]. The security questions, which he was sure about, also provided us with no luck, as they said the information was incorrect. It also said his birthday was incorrect.
Once we called AppleCare, they said the iPad was registered to [email protected], NOT [email protected] (wasn't on the phone with them at this point, otherwise I would have pointed out that the iPad says "[email protected]".) They asked my dad another security question, one he is certain he has never answered before. "The first celebrity you have ever met." My dad hasn't met any celebrities, so he has no idea what that could be. And, they said, no back up email was listed on the account, so the email reset wouldn't work. Even though he has reset his iTunes password several times, using the email method.
The AppleCare technician basically said, "You need a receipt to prove it's yours." The iPad was purchased, new (I was there) from Best Buy 2 years ago. He has been using it for 2 years, with no problems, buying many things with the email address that he assumed was his iTunes/iCloud account. Now he has a locked iPad with no way of knowing how to get it unlocked.
tl;dr My dad had an iPad for 2 years, no problems. Updates to iOS 8.1, says it's locked under a different email than his iTunes email, one with @icloud.com at the end of it. AppleCare says it's registered to his iTunes account email, iPad says otherwise. No receipt, but bought brand new from Best Buy (with cash however) in January of 2012. Security question's answer to reset password is unknown, and "no email is listed" to reset the password (even if he has reset his iTunes password many times).

Answer 1

People often use different Apple and iCloud IDs.  Never understood why, but they do. 
I get that this situation *****.  But from Apple's perspective (and I'm not accusing here) anyone can come into possession of a device and create a scenario as you've described.  Apple can't waver on their rules on resetting devices.  They could be helping a thief, well, get away with stealing.  So Apple is for the right reasons not flexible on this at all.