Is there even some sort of meaningful thread of inter-related events from Sonic the Hedgehog 1 and onward in any capacity, including what Richard refers to as the "Japanese canon"? It's all a bunch of meaningless filler around playing a series of platform style video games. It's not the Lord of the Rings, homey!
If I may be allowed to sperg about Sonic for a moment, maybe I can shine a light on why Kuta freaked out over Ian Flynn's comments. Some Sonic fans take a dogmatic view of the canon. The brief summaries in the Japanese instruction manuals of the Mega Drive games are considered to be the "official" canon for the classic era, everything else is considered secondary including the American instruction manual summaries (which weren't direct translations of the original Japanese sacred texts, but rather a separate story entirely).
Kuta has always been laser-focused on the story and characters from the 1993 animated series Sonic the Hedgehog (SatAM), which shares characters and ideas with the 1993-2017 Archie Comics series. The Sega Genesis was always more successful in North America than its Mega Drive counterpart in Japan, so Sega of America pushed an aggressive campaign to keep Sonic in the spotlight. Since there's very little in terms of story and characters to build on from the games, Sega put together a bible that essentially set up an "American" canon for spin-off material. The reason why the three American Sonic cartoons of the 90's don't resemble the games at all is because the staff of each show were only given brief presentations about the games, so outside of Sonic being fast, Tails being able to fly, and Robotnik being silly the cartoons always skewed away from the games.
When Sonic Adventure came out Sega of Japan took control of the franchise away from Sega of America so they could create one consistent canon, and many elements of the American spin-offs were used in the new "Modern" canon, like Sonic enjoying chili dogs. Supposedly Sega of Japan are incredibly strict about the use of the Sonic I.P., and they weren't happy about Archie continuing with the story lines and characters from Sega of America's 90's canon, but the comic series was so successful that they couldn't reasonably pull the plug on it. They were able to pull the plug after Ken Penders sued Archie and Sega for misuse of characters he created, and now IDW produces Sonic comics with tighter restrictions than Archie had, but with the same writer and artists.
I tried to look up Ian Flynn's comments but couldn't find them, so I don't know exactly what Kuta's going on about, but my guess is that Flynn very reasonably pointed out that Sonic is owned by Sega of Japan and thus they get final say on what Sonic is and what Sonic isn't. Kuta shouldn't be surprised that nobody but him and a dozen other over-30 losers care about SatAM. Even among Sonic fans its not really held in the highest regard, people enjoyed it sure but only the fans focused on SatAM give a shit. His severe lack of self awareness has always been evident, but even more so in this situation because he's sincerely surprised that Sega doesn't give a shit about what he thinks. The fact that he's legitimately offended by the comments of a comic book writer show the state his mind is in. Good on him for being true to himself and liking what he likes, but he's an adult and should know by now that not everyone's going to agree with him that SatAM is the greatest cartoon ever, even beyond licensed cash-ins.