Given that AHA membership numbers are sequential, you only need to know 1 valid number, then keep adding 1 and go again. So it would not be surprising if scalpers took that approach. Even if that didnt work, 1 years membership spread over 14 tickets is no brainer.
The only way a members pre-sale works, is if the ticket is tied to the membership number and the card needs to be presented at the door. But how you make that work for 5,000+ tickets per session I have no idea.