The cover does say "Kyoshi Dana Abbott"
It also says "Includes" Toyama Ryu. Not that it is a Toyama Ryu book.
Unless stated somewhere in the bio that his Kyoshi title was awarded in another art - like Karate - then the only inference can be that it was awarded in Toyama Ryu.
On another note: There is some usefulness in the video series for those with very little to no experience. I would believe he had some Toyama Ryu training perhaps even beyond Shodan-Nidan.