You can buy the AP online - it says 13 months on the web site. They just won't apply it if you bought it literally 5 seconds prior to October 2. I asked if they'd give me the extra month (because it would really hurt their bottom line, you know...)
--- Email from Disney ---
Thank you for contacting the Walt Disney World® Resort.
The current offer of purchasing a new annual pass and receiving 13 months for the price of 12 require purchase an annual pass starting October 2, 2016 to Jan 3, 2017. Renewals is not included in that offer. We are sorry this is not the response that you anticipated; we appreciate your understanding.
If you have questions or need further assistance, feel free to contact us.
--- My Reply (because why not?) ---
Oh, how I wish I could sell my $70,000 in DVC points and quit visiting Disney. If only the family would let me
I am sorry this is not the response that you anticipated; I appreciate your understanding.