I don't understand this, so I need further clarification. Why is his bunkai not traditional? What do you mean by traditional, modern karate which is incorrectly labelled as traditional, or traditional as in his karate used to be before it was changed into what we have now?
I am giving him the benifit of doubt saying his karate is traditional. Having a base in Wado Ryu I would call that traditional. Although his practice of karate could be more influenced by Thompson. Since I don't know the man I will give him the doubt that he keeps his karate training traditional.
That aside, for bunkai to be considered traditional it would have to be the applications that have been passed down from the founder of what ever style we are discussing. In many instances that may go all the way back to the Chinese.
All karate originates from Okinawa. In particular the Shorin styles are the oldest and the history of these kata pass through one man, Matsumura Sokon. Our knowledge of karate prior to him has been lost to time. The kata Matsumura taught have not had any functional bunkai that have been passed down fully intact. The bulk of todays kata found in a wide variety of styles have a predominant feature of being rehashed and reconfigured movements of the original Matsumura kata.
Since we do not have a functional knowledge of Matsumura kata and bunkai it should be understood that a definitive bunkai for today's kata would also be lacking in a concise application and defined technique.
This leads us back to history. The question arises, did Matsumura not teach bunkai? Did he understand the applications himself, was his own learning deficient? We would expect that if he knew kata bunkai he would have passed that knowledge down and likewise Itosu and Funakoshi and all the other masters would have done the same.
Going back to Abernethy, the only possible way he could be resurrecting lost bunkai would be to travel to China and in a 1 in a billion chance find that original form ,,which would also have to be unchanged by time.
Abernethy is creating new bunkai based on his own understanding of mechanics and combat. He is doing nothing more than following the precepts of the Principal & Mechanics concept I stated earlier but then proclaiming his understanding as a single bunkai. The Principal & mechanics concept requires the student to challenge their understanding of kata and create bunkai. The depth of understanding constantly changes the bunkai, , in essence there is no single application.