Yeah, Kron's viewpoint is the result of his grandfather, Helio, and other immediate members of the family being massive ... used car salesmen*, let us say.
*(I have mixed feelings about such an approach to self-promotion. It's not something I really care for, but it was an important part of the art I love becoming successful worldwide and available for me to practice.)
In the early days of Helio's career in self-promotion he made the claim that he and his brothers were the only ones teaching the true authentic Samurai jiu-jitsu in Brazil and that "Judo" was a watered down version created to fool westerners. Later in his career he changed the story to say that he had taken the techniques that Carlos had learned from Maeda and refined them so that they would work for a small, sickly, weak person like himself. (Helio was a college athlete, not sickly or weak.) It's important to note that he only started taking that sole credit for improving the art once his brothers had passed away. Even so, it's not a claim that was universally appreciated in the Gracie family. Carlson Gracie Sr (son of Carlos, nephew of Helio) was the top jiu-jitsu fighter through the 50s and 60s and trained many of the top fighters in the following generation. He had some
strong words regarding Helio.
Rorion, Kron's uncle, was the second Gracie to move to the U.S. and start teaching jiu-jitsu, but he was the first to aggressively promote and market the art. He made connections in Hollywood and the media, marketed video tapes showing BJJ being used to win challenge matches, trademarked the name "Gracie Jiu-Jitsu"**, threatened to sue other members of the extended Gracie clan who used the term, and helped to create the UFC. He also promoted the story of Helio being the singular genius who was the founder or creator of BJJ by virtue of the improvements he had made to Judo.
**(Said trademark was eventually invalidated due to a lawsuit by Carley Gracie, the first Gracie to teach in the U.S.. But by that time people had started calling the art BJJ instead of GJJ.)
Kron's cousins Rener and Ryron (Rorion's sons) are much more respectful towards other martial arts, other branches of the family, and other non-Gracie BJJ practitioners. Even so, they are enthusiastic salesmen and one of their marketing points is the promotion of their grandfather as the founder of BJJ. I don't know whether they honestly believe it because that's what their immediate family told them or if it's just advertising spin.
In any case, BJJ has evolved beyond the Gracie family. They're all very good practitioners and instructors, but their last top-tier world class competitor was Roger Gracie, who is now retired. That's for the best as it allows the art to continue growing and individual members of the Gracie family to just be practitioners like anyone else rather than defenders of a legendary legacy.