He certainly had a big impact on the sale of NS Tbirds.
Vintage Thunderbirds period of low prices was 1975 to 1995. Once the "Guild Guy" started writing about Guild guitars and an article about the Thunderbird old guys like got interested. Thunderbirds were selling less than a $1000 back then if you could find one. After that the prices took off. The Black Key added a little to the increase in Thunderbirds but mostly they provided success for the NS line. Thunderbirds were already in the $5,000 range before the Black Keys made the Thunderbird "popular".
I for one always loved the model from the first time I saw a green Thunderbird being played by cousins boyfriend garrage band in the mid 1960's.
M