Hasbro has since changed that to include anything official. So those who want Peter Cullen to autograph the G1 Optimus Prime they had as a kid of some old Transformers VHS covers you still treasure will be able to.
Here is the updated policy:
Our autograph policy has been updated: HASCON Guests will sign your HASCON Program Guide and only officially licensed DVDs, comics, toys and other collectibles, but they will not sign bootleg merchandise. Please bring only one item to be signed during each autograph session and understand that the HASCON Guests may or may not pose for photographs with the fans. For more information please visit our FAQ's here: Hasbro HASCON 2017