Like most of nutrition "science" the whole thing is a bad joke. There has never been a single high-quality study which showed a significant causative relationship between red meat consumption and worse health outcomes. All of the studies that I've seen have been observational, relied largely on unreliable patient-reported data, had small effect sizes, and failed to control for key confounding variables such as the healthy subject effect.
And what even is "red meat"? Are we talking about corned beef? Bacon? Venison? Grass-fed Argentinian beef? It's such a broad category as to be scientifically meaningless.
I think it's correlation -- people who eat a lot of red meat tend to eat a lot in general -- so it's just a proxy for obesity. That's the usual problem with studies of high protein diets, anyway.
And what even is "red meat"? Are we talking about corned beef? Bacon? Venison? Grass-fed Argentinian beef? It's such a broad category as to be scientifically meaningless.