Not just anybody can walk up and buy this without ever having set foot on an AA aircraft.
This is a program targeted to a specific subset of customers who are falling short of the next level and are willing to pay the incremental out of pocket to get back up. Note that the price to pay it is often more than the price to fly it (MR). In your case you explain the reason right there - you are sitting on 88k miles flown, the system isn't smart enough to add in upcoming miles flown, and thus it thinks that you might not requal for EXP.
Don't be insulted.