This reads like a kneejerk reaction to the title, which I understand. I think it's deliberately written that way to draw you in, but I get how it could be upsetting.

Her point isn't that "fitness is white supremacy," and not even remotely close. Just that the social media and culture around wellness and fitness can give off white supremacist, fascist energy by presenting an extremely unobtainable and yet highly idealized state of being, where everyone is very thin and white and fits within the stereotypes of the gender assigned to them, which is not remotely how the world at large can be.

Actually, reading it again, I don't see the author calling out anyone in particular, just noting that the culture around a thing they otherwise enjoy makes them uncomfortable, and why.