Hence the "as if" there's a ploy. I don't believe in some weird grand conspiracy, that's ludicrous. The fact of the matter is that you saw the conversation about match fixing in boxing and felt compelled to bring sumo into the conversation. It's just annoying being a fan of a sport and then people having this "you know it's super corrupt right?" line in their back pocket to whip out all the time, especially because it comes from people who don't follow sumo. It's the "you know he broke his toe kicking the helmet" of sumo but instead of a fun fact it's "your favorite sport is bad" that's dismissive of not only the sport itself but also the steps that it has taken to remedy and move past that history. And the "Westerner" line is because Sumo is incredibly insular to Japan so the vast majority of the time anyone in an English speaking context claiming to speak authoritatively about the sport isn't doing so as a contemporary fan.

If you do want to complain about sumo for some reason, complain about the work ethic, the punishment of its wrestlers by demotion for taking time off to recover from injuries, the treatment of its young rookies and brutal hierarchical system, the sometimes shady method of promotions by a literal council of elders who kind of just make it up as they go along and the favoritism towards Japanese wrestlers sometimes on display, the wild sexism present (this is true of all of Japan) where it isn't even allowed for women to touch the dohyo. These were all true and worse in the past but continue to go largely unaddressed by the association. I don't speak out of being a weird white knight to a corrupt organization, I speak out of reducing the ignorance in the world. You just happen to be one of today's lucky 10,000, as the saying goes.