[Lordstan]

Brendan,
Unfortunately it happens all the time. While I am a vocal critic of a lot of their work, in all fairness, it can be hard to authenticate every single auto everyone signed. This is especially true since the art of penmanship has taken a tank. The reality is that most forgers will say the same thing that you are. How many people got things in person? How many times have we had my father got it stories? A good authenticator is not swayed by a simple I got it in person story.(BTW I am not implying in any way that you're story is false)
The simple fact is that authenticators only provide an opinion. Their opinion can definitely be wrong, but many take their word as fact and not opinion. If your buyer is one of those people, you really have no recourse.
Sucks, but it is the way the current market works. Only option is to either sell to someone who is not impressed with the alphabets or consign to an auction that will get it certed as part of the sale. They APPEAR to get preferential treatment, so perhaps it would work better that way.

Mark V