Amex has a new algorithm that assesses, prior to them doing a hard pull, whether you are "eligible" (using not only the written terms of the offer, but also their undisclosed internal assessment supposedly based on your history with them-- i.e. how many cards you have, how many you have had, your spending patterns,etc.). If it determines you are not, it gives you the option to just cancel the application.
As I am aware of the new algorithm, this card might be different, especially for current SPG card holders. The offer exclusion mostly include other issuers (Chase), instead of AMEX itself. So the system might just think the person card triggers the no offer again algorithm and deliver the ineligibility message. Just my guess though, not sure how AMEX IT works out...